Ceramics doi: 10.3390/ceramics9090099

Authors: Patrik Sokola Benedikt Polívka Jiří Švec Přemysl Menčík Tina Skalar Marjan Marinšek Martin Sedlačík Matěj Březina David Markusík Petr Ptáček

The long-term storage stability of photocurable alumina suspensions is a critical factor in Digital Light Processing (DLP), yet conventional sedimentation tests provide only limited information about future changes in suspension behavior. This work evaluates analytical centrifugation (LUMiSizer) as a rapid tool for assessing the stability of alumina suspensions stabilized with Disperbyk-103 and Disperbyk-111 dispersants. Rheological measurements, aging tests, and characterization of sintered specimens showed that suspensions with lower instability indices exhibited significantly smaller changes during storage and yielded more reproducible properties after sintering. In particular, the Disperbyk-111 system remained largely unchanged after 20 days of storage, whereas the Disperbyk-103 suspension underwent pronounced rheological aging accompanied by lower density and greater shrinkage after sintering. The results indicate that the instability index obtained by analytical centrifugation provides a useful screening indicator of suspension stability during storage and may serve as a practical tool for selecting dispersant formulations for DLP-based ceramic processing.

Ceramics doi: 10.3390/ceramics9090098

Authors: Gulsu Simsek-Franci Philippe Colomban Tung-Ho Chen Ching-Fei Shih Ludovic Bellot-Gurlet Bing Zhao Pei-Chin Yu

The study of heterogeneous exceptional objects preserved in different places implies the use of various instruments. Here, we compare the manufacturing techniques of two rare enameled glasses (a box and a vase) made for the Kangxi Emperor (r. 1661–1722) using XRF analyses performed in the laboratory for one object and with a mobile spectrometer for the other. The enamels are identified and compared based on the characteristic signals of different chemical elements, with or without multivariate analysis. Although the bodies have similar compositions (but differ in trace elements) and are opacified with calcium arsenate, large differences are observed for certain enamels: the red of the box is obtained using the traditional Chinese method based on copper nanoparticles, while the brown and purple to pink of the vase use gold nanoparticles, a recipe imported from Europe. The white highlights of the box are opacified with tin. Cobalt is rich in arsenic and contains bismuth and nickel, consistent with European importation as reported in historical sources. Naples yellow is used in both objects. A comparison of the distinctive features of these objects with those of painted enameled imperial porcelain and cloisonné enamelware further highlights the technological exchanges and material choices involved in the production of imperial decorative objects, as well as the very innovative ‘research’ conducted at the imperial glass workshop.

Ceramics doi: 10.3390/ceramics9090097

Authors: Yingji Li Yao Han

Alumina (Al2O3) ceramic sealing rings have attracted considerable attention in power battery packaging applications due to their excellent chemical stability, electrical insulation, and mechanical properties. In this study, 95% Al2O3 ceramics were fabricated using a CaO–SiO2–TiO2–ZrO2 quaternary sintering aid system, and the effects of the TiO2/ZrO2 ratio on densification behavior, microstructural evolution, mechanical properties, and Mo–Mn metallization bonding performance were systematically investigated. As the TiO2/ZrO2 ratio decreases, the grain size first increases and then decreases, which is attributed to the pinning effect of the Al2TiO5 phase formed by excessive TiO2 at grain boundaries that inhibits grain growth, whereas an appropriate TiO2/ZrO2 ratio promotes grain growth. After sintering at 1600 °C and 1625 °C, the density first increases and then decreases with decreasing TiO2/ZrO2 ratio; at 1650 °C, accelerated grain boundary migration engulfs residual pores into grain interiors, reversing the density trend. The flexural strength exhibits a rise–and–fall pattern with decreasing TiO2/ZrO2 ratio at all sintering temperatures, governed by the synergistic interplay among densification, grain size, and grain boundary characteristics. The metallization tensile strength first decreases and then increases with decreasing TiO2/ZrO2 ratio for ceramics sintered at 1600 °C and 1625 °C, but shows the opposite trend for those sintered at 1650 °C, governed by the glass–phase diffusion capability and surface roughness, respectively. The Al–2–2 sample (TiO2/ZrO2 = 1/1) sintered at 1650 °C exhibits the optimal overall performance, achieving a flexural strength of 351 ± 46 MPa and a metallization tensile strength of 153 ± 2 MPa.

Ceramics doi: 10.3390/ceramics9090096

Authors: Ahmad Kassas U-Chan Chung Nicolas Penin Julien Lesseur Dominique Bernard Catherine Elissalde Mario Maglione

The preparation of TiO2 microspheres by spray drying followed by controlled sintering was investigated. Starting from commercial rutile TiO2 nanoparticles dispersed in water, spherical microspheres with broad size distributions were produced by adjusting key spray-drying parameters, including solid concentration, gas flow, and suspension composition. The results showed that controlling the spray-drying conditions and the subsequent sintering cycle influenced the resulting microsphere size and morphology, grain evolution, and porosity. A tailored multi-step sintering approach was used to control the microstructural evolution of individual TiO2 microspheres while limiting inter-microsphere coalescence. SEM and three-dimensional nano-tomography revealed pronounced grain growth and progressive pore elimination during sintering. The grain size increased from approximately 2–5 µm at 1200 °C to 20–40 µm at 1400 °C, while ex situ nano-tomography showed a decrease in pore volume fraction from 15.9% to 1.3% over the same temperature range. In situ nano-holotomography further confirmed the progressive reduction in the connected pore network during heating. Overall, sintering at 1400 °C provided the best compromise between densification, grain growth, microsphere isolation, and preservation of the spherical morphology.

Ceramics doi: 10.3390/ceramics9090095

Authors: Leszek Klimek Michał Wilk Beata Śmielak

Prosthetic restorations made of titanium and its alloys are often veneered with ceramics. While Co-Cr or Ni-Cr alloys are subjected to high-temperature oxidation before ceramic application, this is not possible for titanium due to its high reactivity; hence, the resulting layers are thick, porous, and have poor adhesion. An alternative method for obtaining an oxide layer is anodic oxidation, or anodization. This paper presents the shear strength of the titanium–ceramic bond after different anodization variants. The following reagents were used for oxidation: Group A—1 molar phosphoric acid (V), Group B—1 molar sulfuric acid (VI), Group C—1 molar mixture of the above acids, and Group D—2% Na2SiO3 at pH = 13.1. The veneering ceramic was applied to the treated sample surfaces, and the samples were subjected to a shear test. Anodic oxidation was found to increase the joint stress compared to a control group of unanodized samples (Group 0). The highest strength was achieved for samples from groups A and B. Hence, anodic oxidation improved the titanium–ceramic adhesion of polished samples compared to the control group.

Ceramics doi: 10.3390/ceramics9090094

Authors: Rafael Gonçalves Hammes Thamires Alves da Silveira Rafaella dos Passos Nörnberg Rafael Beltrame Rafael de Avila Delucis

Natural fiber-reinforced geopolymer and alkali-activated composites have emerged as promising alternatives for reducing the environmental impact of cement-based materials; however, their long-term durability remains insufficiently understood. This systematic review evaluates the durability behaviour of natural fiber-reinforced geopolymer and alkali-activated composites based on 42 studies published between 2017 and 2025, identified from 356 records retrieved from Scopus and Web of Science following the PRISMA methodology. The literature analysis reveals a significant increase in research activity in recent years, with 12 studies published in 2025 alone, indicating a growing transition from mechanical-performance evaluation toward durability-oriented design. The reviewed studies investigated multiple degradation environments, including moisture cycling, freeze–thaw exposure, chemical attack, carbonation, and thermal ageing. Across the evidence base, durability performance was mainly governed by the interaction among binder chemistry, pore structure, curing conditions, fiber characteristics, surface treatments, and exposure severity. Notably, the intrinsic surface properties of different natural fibers, including hydrophilic character, surface chemistry, and surface roughness, were found to strongly influence moisture absorption, fiber–matrix adhesion, and susceptibility to alkaline degradation, thereby contributing to distinct durability outcomes among fiber types. Fiber modification strategies and optimized matrix designs were frequently associated with improved interfacial stability and mechanical retention after ageing, whereas excessive fiber contents and poorly controlled moisture transport were recurrent factors contributing to degradation. Despite these advances, the review identified significant methodological limitations, particularly the lack of standardized durability protocols and long-term exposure assessments. Future research should prioritize harmonized testing approaches and integrated durability-based design frameworks to enable reliable prediction of service performance in natural fiber-reinforced alkali-activated composites.

Ceramics doi: 10.3390/ceramics9090093

Authors: Aleksandar Savić Ivana Jelić Dragi Antonijević Jakob Šušteršič Marija Šljivić-Ivanović

Construction and demolition waste (C&DW) has been investigated both for radionuclide sorption and as a precursor for geopolymer materials. However, research on C&DW-derived geopolymers has primarily focused on synthesis and characterization, while their role in radionuclide immobilization remains insufficiently explored. This review evaluates C&DW-derived geopolymers as promising matrices for radionuclide immobilization, focusing on retention capabilities and factors influencing immobilization performance. Available studies indicate that waste-derived geopolymer systems can limit radionuclide mobility and leaching, but their performance strongly depends on precursor composition, phase assemblage, and matrix structure. The mineral complexity of C&DW-derived matrices may provide diverse retention pathways, supporting their consideration as immobilization materials. Linking the documented sorption capacity of C&DW materials with the immobilization potential and favorable characteristics of C&DW-derived geopolymer matrices represents a promising approach for developing advanced systems for radionuclide solidification. Due to the limited number of studies directly addressing radionuclide immobilization in C&DW-derived geopolymer systems, evidence from related studies is considered to support assessment of their immobilization capacity. Nevertheless, further clarification is required regarding the integration of existing research findings, precursor heterogeneity, multi-ion interactions, and long-term performance under realistic conditions. Addressing these limitations through systematic investigations is essential to support their application in radioactive waste (RW) management.

Ceramics doi: 10.3390/ceramics9090092

Authors: Mina Yahia Falih Manhal Abdulrahman Majeed

A novel lithium disilicate glass-ceramic modified with Pyrex-derived borosilicate glass and antimony oxide was developed to improve mechanical performance while maintaining chemical stability. The material was fabricated by oxide mixing, melt-quenching, casting, and controlled crystallization, followed by structural and microstructural characterization using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Flexural strength, Vickers hardness, and chemical solubility were evaluated according to the relevant ISO standards and compared with those of a commercial lithium disilicate glass-ceramic (IPS e.max CAD; Ivoclar Vivadent, Schaan, Liechtenstein). Statistical analyses were performed using independent-samples t-tests at a significance level of α = 0.05. Structural characterization demonstrated a multiphase crystalline glass-ceramic containing reflections consistent with lithium disilicate, while FE-SEM revealed elongated, partially interlocking crystals distributed within the residual glassy matrix, confirming the development of the intended glass-ceramic microstructure. The experimental material exhibited significantly higher flexural strength than the commercial reference (560.41 ± 53.31 MPa vs. 371.39 ± 14.48 MPa; p < 0.05), whereas Vickers hardness and chemical solubility did not differ significantly between the materials (p > 0.05). These findings suggest that the incorporation of Pyrex-derived borosilicate glass as a glass-network modifier, together with antimony oxide, may provide a viable approach to producing lithium disilicate glass-ceramics with enhanced flexural performance while maintaining hardness and chemical durability, supporting their potential for dental restorative applications.

Ceramics doi: 10.3390/ceramics9090091

Authors: Nursultan Rakhym Sanat Tolendiuly Aigerim Sovet Sergey Fomenko Ilhamsyah Putra Abu Bakar Nur Akasyah Binti Jaafar Sharafkhan Assilkhan Karakat Bolatzhan

The effect of Co3O4 concentration on the phase composition, surface morphology, geometric density, estimated porosity, compressive strength, and resistive superconducting transition of YBa2Cu3O7−δ ceramics was comparatively investigated. Undoped YBa2Cu3O7−δ and Co3O4-modified YBa2Cu3O7−δ ceramics containing 0.1, 0.5, 1.0, and 1.5 wt.% Co3O4 were prepared from the same nonstoichiometric Y–Ba–Cu–O precursor mixture by a solid-state reaction route followed by oxygen annealing. Phase composition was evaluated by X ray diffraction, surface morphology by scanning electron microscopy, geometric density from specimen mass and dimensions, compressive strength by uniaxial compression, and superconducting transition parameters by four probe electrical resistance measurements. The YBa2Cu3O7−δ phase remained the dominant crystalline phase in all specimens. The sample containing 0.1 wt.% Co3O4 exhibited the highest YBa2Cu3O7−δ content among the modified specimens, 65.2 wt.%, the highest measured compressive strength of 1.95 MPa, and the highest onset transition temperature of 95 K. The highest geometric density of 5.36 g/cm−3 and the lowest estimated porosity of 15.3% were obtained at 0.5 wt.% Co3O4. The specimens containing 1.0 and 1.5 wt.% Co3O4 showed lower YBa2Cu3O7−δ phase fractions and lower geometric density, and did not reach the zero-resistance state within the available measurement range. Although the 0.1 wt.% specimen exhibited a higher onset temperature than undoped YBa2Cu3O7−δ, its lower zero-resistance temperature and broader transition indicate that Co3O4 did not improve all superconducting parameters simultaneously. Since only one specimen was tested for each composition, the density and compressive strength trends should be regarded as preliminary.

Ceramics doi: 10.3390/ceramics9090090

Authors: Guillermo Monrós José Badenes Mario Llusar Vicente Esteve Guillem Monrós-Andreu

A CMY palette of ceramic pigments was synthesized using both microwave-assisted firing (800 W, 30 min) and conventional electric firing (1000 °C for 3 h). For the allochromatic vanadium-zircon system (including the non-mineralized green and halide-mineralized blue compositions), as well as the chromium-doped scheelite yellow pigment, microwave firing does not outperform conventional calcination. Although comparable reactions occur during synthesis, microwave firing produces powders with lower colour performance. Nevertheless, these differences become visually negligible after incorporation into glazes. This behaviour can be attributed to the low dopant concentration and the localized, selective heating characteristic of microwave irradiation. In the vanadium-zircon system, the microwave-mineralized sample exhibits features similar to those of the non-mineralized compositions, including lower reactivity, smaller crystallite size, and enhanced blue colour development when applied in glazes. In contrast, for the idiochromatic Zn(Al1.3Fe0.5Cr0.2)O4 spinel red-brown pigment, microwave firing yields superior colour performance compared with conventional electric firing, producing higher chroma and greater colour intensity. In idiochromatic pigments, the relatively high proportion of chromophore components promotes more homogeneous microwave absorption and heating throughout the precursor mixture. The enhanced colour properties achieved through microwave synthesis may indicate the presence of a beneficial non-thermal microwave effect, leading to improved chromatic performance.

Ceramics doi: 10.3390/ceramics9080089

Authors: Natali López García Adriana Báez Rodríguez Luis Zamora-Peredo Óscar Velázquez-Camilo Rafael Martínez-Martínez Ciro Falcony-Guajardo Omar Solorza-Feria Manuel García-Hipólito Pablo Cardoso-Ávila Jaime Martínez-Castillo Amado Carlos García-Velasco

A homogeneous photocatalyst on a stable substrate is required for photocatalytic reactors in wastewater treatment. ZnO films were synthesized on stainless steel prepared by the spray pyrolysis technique at different deposition temperatures (350 to 500 °C in steps of 50 °C). Scanning electron microscopy showed microflowers formed by nanopetals with an average size of 2 μm. The ZnO wurtzite structure and its defects were studied by Raman spectroscopy, X-ray diffraction, diffuse reflectance, and photoluminescence spectroscopy. A deposition temperature of 400 °C was chosen due to the presence of a higher number of vibrational modes, better distribution of microflowers, smaller crystallite size and a higher number of defects than the other options. Lanthanides were incorporated into ZnO by solution spraying, and then thermal treatment was performed at 600 °C. The photocatalytic evaluation of ZnO showed the best photocatalytic activity under UV light at 365 nm with a 69.34% degradation efficiency at 120 min. Photocatalytic activity toward methylene blue degradation was enhanced in ZnO:Ce3+ (2 and 4 atom%) and ZnO:Nd3+ (0.05 and 2 atom%) samples, achieving degradation efficiencies above 90% within 30 min of UV–visible light irradiation.

Ceramics doi: 10.3390/ceramics9080088

Authors: Christian Bartsch Vera Kerling Tomokatsu Hayakawa Dominique de Ligny Maria Rita Cicconi

Lanthanide-doped Ca2Nb2O7 offers versatile and tunable luminescence properties. Previous studies have shown that Pr3+-doped and Pr3+/Er3+ co-doped Ca2Nb2O7 ceramics exhibit non-destructive mechanoluminescence, up- and down-conversion luminescence, and thermoluminescence, with potential for optical temperature sensing. However, to date, niobate glass–ceramics (GCs) remain largely unexplored, although they would offer excellent temperature resistance, high chemical durability, controllable crystallization, and the possibility to combine functional properties. This study investigates Pr3+ single doping and Pr3+/Er3+ co-doping in glass–ceramics prepared from niobium-containing calcium aluminosilicate glasses with the composition 55CaO-(35-x)Al2O3-10SiO2-xNb2O5 (mol%, where x = 0, 10). The aim is to obtain glass–ceramics containing Ca2Nb2O7 crystals with a layered perovskite structure and to evaluate their suitability as hosts for rare-earth ions. The luminescence properties of both parent glasses and GCs were investigated, and it is shown that the glasses show intrinsic luminescence which, when doped, enables sensitization of rare-earth elements via charge transfer. Furthermore, several interesting photoluminescence mechanisms were observed in the doped GCs, including (i) Er3+ up-conversion from the NIR to the visible, (ii) variations in the relative intensities of Er3+ hypersensitive transitions, reflecting changes in site symmetry, and (iii) a charge transfer process to the activator ions under UV excitation. These phenomena extend the accessible excitation range for rare-earth emission. Overall, the developed Ca2Nb2O7 GCs demonstrate efficient dopant integration, confirming their suitability as lanthanide hosts for advanced photonic, sensing and energy conversion applications.

Ceramics doi: 10.3390/ceramics9080087

Authors: Lincoln Pinoski Carter Stone Alec Viloria Bobbie VanSant Chris Velasco Pradeep L. Menezes

Perovskite solar cells (PSCs) have emerged as one of the most rapidly advancing photovoltaic technologies of the past decade, progressing from the initial demonstration of 3.8% power conversion efficiency (PCE) in 2009 to certified single-junction efficiencies exceeding 26% and perovskite–silicon tandem efficiencies exceeding 33.9% as of 2024. Their appeal resides in the combination of a broadly tunable bandgap achieved through compositional engineering of the ABX3 perovskite crystal structure, compatibility with low-temperature solution processing, and the potential for manufacturing costs substantially below those of silicon photovoltaics. However, the translation of laboratory-scale performance to commercially viable modules at industrial throughput remains the central challenge in the field. This review provides a comprehensive and critically organized account of PSC manufacturing, spanning device architectures and material requirements, scalable deposition and coating technologies, charge transport layer integration and interface engineering, process control and crystallization strategies, post-treatment methods, artificial intelligence and machine learning-assisted manufacturing, module fabrication and encapsulation, advanced tandem and flexible device configurations, green chemistry and circular lifecycle strategies, and the critical barriers to commercialization. The review concludes with a strategic assessment of the technological, regulatory, and economic requirements for PSC technology to transition from pilot-scale demonstration to utility-scale deployment.

Ceramics doi: 10.3390/ceramics9080086

Authors: Dušan Bučevac Marko G. Nikolić Miomir Krsmanović Nada Adamović Ljiljana Kljajević Snežana Nenadović Mia Omerašević

Dense Ce,Pr-doped YAG transparent ceramics (YAG:Ce,Pr) with enhanced red emission were fabricated by pressureless sintering in air at 1600 °C. Fine YAG powders containing 0.2 mol% Ce and varying amounts of Pr (0.04–0.32 mol%) were synthesized using a glycine–nitrate combustion method. The emission and excitation spectra were analyzed to investigate the influence of Pr doping on red emission. The results indicate that YAG: Ce,Pr ceramics are a promising candidate for blue-to-yellow light conversion. The strongest red emission component was measured in samples containing 0.16 mol% Pr. It was confirmed that electron transfer from Ce to Pr enhances the red emission component (609 nm), primarily by increasing the population of electrons relaxing from the 1D2 excited state to the 3H4 ground state. Further increasing the Pr concentration beyond 0.16 mol% resulted in a reduction in the red emission intensity due to concentration quenching. Microstructural analysis of YAG:Ce,Pr revealed a dense and homogeneous microstructure composed of equiaxed grains.

Ceramics doi: 10.3390/ceramics9080085

Authors: Yar Mohammed Miwan Salahalddin Abdulrahman

This in vitro study evaluated the effect of two silane coupling agent application techniques (dry air and thermally activated warm air) on the interfacial properties and shear bond strength (SBS) of lithium disilicate veneers fabricated with two designs: incisal overlap and window. Materials and Methods: The interfacial characteristics of lithium disilicate specimens were evaluated using contact angle measurements and ATR–FTIR spectroscopy to investigate the effect of different silane application techniques. Forty lithium disilicate veneer specimens were divided by preparation design (incisal overlap or window) and silane application technique (dry air or warm air) (n = 10). Forty flat lithium disilicate specimens were prepared for contact angle and ATR–FTIR analyses. Wettability was assessed using the sessile drop method, while SBS was measured using a universal testing machine. ATR–FTIR evaluated chemical changes within the silane layer. Results: Warm-air silane application significantly improved SBS and wettability compared with dry-air application. The incisal overlap/warm-air group exhibited the highest SBS (19.3 ± 1.7 MPa), whereas the window/dry-air group showed the lowest (12.5 ± 1.4 MPa). Contact angle measurements demonstrated significantly lower values following thermal activation (p < 0.001). ATR–FTIR analysis suggested modifications in carbonyl-containing organic species at the interface following thermal activation. Conclusions: Thermal activation of silane improved interfacial properties and bond strength. Incisal overlap preparations demonstrated superior bonding performance, while warm-air silane application enhanced adhesion across both designs.

Ceramics doi: 10.3390/ceramics9080084

Authors: Sanat Tolendiuly Nursultan Rakhym Kaster Kamunur Sharafkhan Assylkhan Aisulu Batkal Dinara Muktaly Olesya Tyumentseva

A comparative compositional screening of combustion behavior and phase formation during self-propagating high-temperature synthesis in B2O3–Al–C and B2O3–Mg–C mixtures was performed under the same open-air laboratory conditions. Twelve strongly carbon-rich formulations were examined. These formulations were not intended to reproduce the target stoichiometric reactions and are interpreted as an empirical screening matrix rather than as optimized stoichiometric compositions. In the individual SHS runs, the Mg-containing formulations produced higher recorded maximum apparent local combustion front temperatures and estimated apparent average front propagation velocities than the Al-containing formulations. Because each formulation was tested only once, these observations do not establish reproducible differences between the two systems. Qualitative X-ray diffraction analysis identified Al2O3, Al20B4O36, Al4B2O9, and residual Al in the aluminothermic products. MgO, Mg2B2O5, and Mg3B2O6 were identified in the magnesiothermic products. Weak reflections attributable to B4C were observed in selected compositions, whereas oxides and metal borates were the principal crystalline phases identified in both systems. This result indicates that the carbide-forming pathway was competitively disadvantaged under the investigated open-air SHS conditions. Thermodynamic calculations for the idealized reactions showed that the relative standard driving force depended on temperature and the phase states of the reactants and products. The final phase assemblages indicate competition between carbide formation and the formation of stable oxide and borate phases. Atmospheric oxidation may also have contributed to the oxide-rich products. The results provide a descriptive comparison of the two investigated formulation sets and identify compositional patterns associated with limited B4C formation under open-air SHS conditions.

Ceramics doi: 10.3390/ceramics9080083

Authors: Azmi Mert Çelik Richard A. Haber Adrian B. Mann

TiB2 ceramics have a wide range of applications due to their exceptional properties. However, high relative density must be achieved to enable their use in cutting tools, wear-resistant components, body armor, and extreme environment applications. In this study, high-purity TiB2 powders with hexagonal platelet-like morphology were synthesized through boro/carbothermal reduction reactions under Ar flow. In-house synthesized and commercial TiB2 powders were consolidated via spark plasma sintering. The effects of oxygen content, sintering temperature, and hold time on the microstructure, elastic and mechanical properties of monolithic TiB2 ceramics were investigated. The highest relative density of 99.43%, elastic modulus of 541 GPa, and Vickers microhardness of 40.35 GPa were achieved at 1750 °C for a hold time of 45 min. The exceptional properties, among the highest achieved for spark plasma sintered monolithic TiB2, are attributable to preferential kinetic conditions and the powder’s morphology.

Ceramics doi: 10.3390/ceramics9080082

Authors: Gokce Naz Comert Bebek Serra Ahmet Oguz

This in vitro study evaluated the effects of simulated gastric acid exposure on surface roughness, color change, translucency, and mass change in four monolithic CAD/CAM restorative materials with different microstructural compositions. Rectangular specimens (12 × 14 × 1 mm; n = 12/group) were prepared from a polymer-infiltrated ceramic network material (VITA Enamic), a zirconia-reinforced lithium silicate glass-ceramic (Celtra Duo), a resin nanoceramic (Cerasmart), and a lithium disilicate glass-ceramic (IPS e.max CAD). After standardized finishing and polishing, baseline measurements of surface roughness, color coordinates, translucency, and mass were obtained, and the specimens were then individually immersed in simulated gastric acid (0.06 M HCl, pH 1.2) at 37 °C for 96 h, with the solution renewed every 24 h. Post-exposure measurements were performed using the same protocols. Data were analyzed using the Shapiro–Wilk test, Kruskal–Wallis test with Dunn’s post hoc comparisons, and Wilcoxon signed-rank test (α = 0.05). Significant changes were observed after acid exposure, and the magnitude of these changes varied among materials. Surface roughness increased significantly in all groups, with the greatest increase detected in Celtra Duo and VITA Enamic. Measured mass also changed significantly in all groups; VITA Enamic showed a slight increase, whereas Celtra Duo, Cerasmart, and IPS e.max CAD showed slight decreases. Although statistically significant differences in color change and translucency were identified among the groups, all color changes remained below the clinically perceptible threshold, indicating limited optical impact under the present model. IPS e.max CAD exhibited the lowest color change, whereas Cerasmart showed the highest ΔE00 values. Within the limitations of this accelerated in vitro model, simulated gastric acid exposure caused material-dependent alterations in surface roughness, limited optical changes, and small measured mass changes in monolithic CAD/CAM restorative materials.

Ceramics doi: 10.3390/ceramics9080081

Authors: Da Jung Kang Gi Bbum Lee

This study investigates the key material properties governing the long-term stability of ceramic heat-storage media exposed to severe high-temperature and high-humidity conditions (up to 950 °C under high-steam partial pressure). Candidate ceramics, including high-purity alumina, mullite, and cordierite compositions, were evaluated through physical property measurements, chemical composition analysis, SEM–EDX microstructural characterization, and hydrothermal corrosion simulations. Ceramics containing significant SiO2 exhibited chemical weakening due to steam-induced silica dissolution and the formation of hydroxyl-rich surface layers. However, the overall mechanical integrity was predominantly limited by thermal shock failure occurring during rapid heating–cooling cycles and repeated steam condensation and evaporation. The results demonstrate that ceramics with a low coefficient of thermal expansion (CTE ≈ 2–4 × 10−6/K) show markedly enhanced resistance to thermal shock, leading to improved operational durability. In addition, low open porosity (<10 vol%) effectively restricted internal steam penetration and reduced the rate of hydrothermal degradation, particularly in SiO2-based systems where pore-connected pathways accelerate corrosion. These findings indicate that thermal shock resistance, enabled by intrinsically low CTE, together with reduced porosity, constitutes the primary design criterion for ensuring the structural reliability of ceramic heat-storage components operating in high-humidity thermal environments.

Ceramics doi: 10.3390/ceramics9080080

Authors: Michael I. Ojovan

Crystalline solids melt at well-defined material-specific temperatures Tm via first-order phase transitions, whereas glasses undergo continuous transformations from solid to molten states at glass transition temperatures Tg, resembling second-order transitions. Despite extensive study, the microscopic origin of this distinction remains unveiled. In this work, both melting and glass transition are described within a unified framework based on analysis of thermally activated breakings of chemical bonds, treated as elementary excitations of condensed matter, termed configurons. The increasing concentration of configurons leads to a percolation transition corresponding to loss of mechanical rigidity of an elastic solid whose atoms are connected via chemical bonds. Configurons are delocalized and mobile in crystals, enabling their condensation and consequent latent heat release, whereas in glasses they are localized (Anderson localization), suppressing condensation and yielding a continuous transition from solid to molten states. The proposed framework provides a unified physical interpretation of phase transitions.

Ceramics doi: 10.3390/ceramics9080079

Authors: Husam Ahmad Nils Schmeißer Maik Trautmann Raouf Abdou Ngoc Tu Tran Andreas Seefried Guntram Wagner

Production of short-fiber-reinforced carbon/carbon composites (SF-C/C composites) is typically based on the pyrolysis of short-fiber-reinforced plastics (CFRPs) produced by compression molding. The production of C/C composites is generally a highly time- and energy-intensive process, particularly for complex geometries. Injection molding can offer an attractive alternative due to its high level of automation, cost efficiency, and ability to produce complex geometries. However, in contrast to compression molding, the shorter fiber lengths resulting from the compounding process and the parameter/geometry-dependent cavity-filling behavior in injection molding lead to a complex three-dimensional fiber orientation distribution. This can profoundly affect both the pyrolysis behavior of the CFRPs and the properties of the resulting SF-C/C composites. In this study, CFRP plates (150 × 150 × 4 mm3) were injection-molded at varying injection rates and mold temperatures. The influence of these parameters on the properties of the resulting SF-C/C composites was systematically investigated. Characterization included shrinkage and warpage behavior, porosity, microstructure via light microscopy and X-ray computed tomography, and flexural properties. The results show that the homogeneity of fiber orientation within the component is critical for controlling warpage during pyrolysis. In particular, asymmetric flow-line formation leads to non-uniform shrinkage across the thickness and promotes warpage. Therefore, achieving a homogeneous and/or symmetric distribution of the fiber orientation is essential for producing warpage-free SF-C/C composites by injection molding.

Ceramics doi: 10.3390/ceramics9080078

Authors: Arseny N. Kiryakov Yulia A. Kuznetsova Evgeny A. Buntov Tatyana V. Dyachkova Alexander P. Tyutyunnik

High-entropy oxide (HEO) nanoceramics based on (Y0.2La0.2Gd0.2Eu0.2Er0.2)2O3 were synthesized at 600 °C for 10 min under pressures of 2, 4, 6, and 8 GPa using High-Pressure–Low-Temperature (HPLT) technology, and the resulting structural, phase, and optical changes were studied as a function of synthesis pressure. X-ray diffraction with Rietveld refinement showed that the initial single-phase cubic nanopowder decomposes under pressure into a mixture of cubic, monoclinic, and orthorhombic high-entropy phases: the cubic fraction falls from 67.3% at 2 GPa to 46.8% at 4 GPa, 42.9% at 6 GPa, and 31.1% at 8 GPa, while low-symmetry monoclinic and orthorhombic inclusions become correspondingly more abundant. Raman spectroscopy validated this evolution, with the 2 GPa sample showing a resolvable doublet near 364 and 353 cm−1 attributable to two coexisting cubic phases, while samples synthesized at 4–8 GPa converge on a single narrow band at 353 cm−1 that broadens with increasing pressure. Photoluminescence measurements revealed that the sample synthesized at 2 GPa exhibits the highest Eu3+ and Er3+ luminescence intensity, with emission and excitation intensities decreasing systematically as synthesis pressure increases. We attribute this decline to the growing fraction of low-symmetry monoclinic phase, whose C2h point-group sites impose parity-forbidden selection rules on the 5D0 → 7FJ transitions of Eu3+, combined with an increased probability of nonradiative relaxation at structural defects introduced by pressure. These results establish synthesis pressure as a practical lever for tuning the phase composition and luminescent efficiency of multi-lanthanide HEO nanoceramics and indicate that low pressures (~2 GPa) are preferable for optical applications requiring high luminescence intensity.

Ceramics doi: 10.3390/ceramics9080077

Authors: Camilla Kärnfelt Maïna Sinou

This study presents an initial effort to develop Low-Temperature Cofired Ceramics (LTCC) using local bio-sourced materials: Saint Jacques shells and slate tiles. Chemical analysis confirms that the Saint Jacques shells provide CaO and CaCO3, while slate supplies the needed SiO2 and Al2O3. The constituents, processed from a formulation targeting 70 wt% slate and 20 wt% shell fragments are crushed and ball-milled, mixed with 10 wt% boron trioxide (B2O3), and calcinated at 700 °C for two hours to remove organics, followed by a second milling. An aqueous slurry is then prepared and manually tape-cast to form tapes that are processed through standard LTCC process steps. Initial green-state mechanical tests showed elongation values up to ~7.8% and tensile break forces in the range of ~0.5–1.0 N, with lamination performed successfully using standard isostatic conditions. Cofiring yielded limited lateral shrinkage (~6%) but substantial vertical shrinkage (27%). Two-line method measurements indicate a relative permittivity of approximately 4.3 with a comparatively high loss tangent of 0.03, suggesting a vitreous phase and/or porous, inhomogeneous microstructure. A final resonator prototype is fabricated, yielding somewhat encouraging results for the feasibility of this bio-sourced LTCC route while highlighting the need to reduce dielectric losses in future work.

Ceramics doi: 10.3390/ceramics9080076

Authors: Lilan Liu Jiayi Wang Yingkai Qin Boyu Guo Qifan Luo Qiang Xu

To realize the remanufacturing of cast iron components, a WC-reinforced Fe-based composite powder was designed, and the WC/Fe-based composite coating was deposited on the HT250 substrate by laser cladding. The melting and dissolution mechanism of WC ceramic particles were investigated, and their influences on the microstructure, phase, microhardness, and wear resistance of the composite coatings were systematically analyzed. The results show that the WC/Fe-based composite coating achieves good metallurgical bonding with the HT250 substrate and possesses excellent forming quality. The incorporated WC particles can effectively optimize the microstructural morphology, acting as heterogeneous nucleation sites and inhibiting grain growth. As WC content increases, the grain size within the composite coating gradually refines. Moreover, partially melted WC particles release tungsten (W) and carbon (C) elements into the molten pool, promoting the in-situ generation of new hard phases, including W2C and Fe6W6C. These newly formed phases, together with the residual unmelted WC particles, contribute a dispersion strengthening effect and improve the properties of the composite coatings. This effect becomes more pronounced with higher WC content. Notably, the composite coating with 20% WC exhibits a microhardness over twice that of the HT250 substrate, while its wear rate is only one-sixth that of the substrate and its corrosion resistance is much higher than that of the HT250 substrate.

Ceramics doi: 10.3390/ceramics9080075

Authors: Fukai Lu Shaohua Su Bijun Fang Shuai Zhang Xiaolong Lu Jianning Ding

(Bi0.5Na0.5)TiO3 (BNT)-based ceramics have attracted much attention for energy storage applications, but some fundamental issues remain unclear—in particular, how the conduction mechanism changes with composition and what role oxygen vacancies play. The (0.95−x)[(Bi0.5Na0.5)(1−1.5y)Smy](Zr0.2Ti0.8)O3-0.05BiFeO3-xBa(Sn0.2Ti0.8)O3 (abbreviated as (0.95−x)BNSmZT-0.05BF-xBaSnT, x = 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, y = 0.01) system was investigated, where Ba(Sn0.2Ti0.8)O3 (BaSnT) content varies from 0.05 to 0.4. A non-monotonic conduction transition is revealed by the conductivity and relaxation behavior characterized by impedance spectroscopy and dielectric temperature spectra combined with electric modulus analysis. At low BaSnT (x ≤ 0.1), residual Bi2Ti2O7 at grain boundaries blocks oxygen vacancy migration, giving high activation energy (~2.12 eV) and presenting oxygen vacancy-mediated conduction. At x = 0.15, the impurity disappears and free oxygen vacancies surge, dropping the activation energy to 1.21 eV, corresponding to oxygen-vacancy-dominated ionic conduction with increased carrier density. For x = 0.2–0.4, strong Ba-O-Bi bonds stabilize the migration barrier around 1.57 eV, resulting in mixed oxygen vacancy-mediated conduction. The optimal composition 0.75BNSmZT-0.05BF-0.2BaSnT shows the best dielectric stability and highest resistance. From modulus master curves and broadened M″ peaks, the conduction is identified as correlated hopping of oxygen vacancies, consistent with non-Debye relaxation. This work provides a clear picture of how oxygen vacancy dynamics depend on phase purity, grain boundaries, and A-site chemistry in the BNT-based lead-free ceramics.

Ceramics doi: 10.3390/ceramics9080074

Authors: J. Theo Kloprogge

Thermal treatment of clay minerals induces a sequence of dehydration, dehydroxylation, and recrystallization reactions that control the properties of ceramic materials, calcined clays, and other high-temperature products. This review examines how vibrational spectroscopic techniques, particularly Fourier-transform infrared (FTIR), Raman, and infrared emission spectroscopy (IES), have advanced the molecular-level understanding of these transformations. Unlike conventional thermal analysis methods, these techniques directly monitor changes in hydroxyl groups, interlayer water, silicate frameworks, and newly formed phases during heating, providing real-time insight into reaction pathways and intermediate structures. The thermal behavior of major clay mineral groups, including kaolinite-group minerals, serpentines, smectites, illite, palygorskite, sepiolite, and mixed-layer clays, is compared in terms of their characteristic spectroscopic responses to increasing temperature. Particular attention is given to band shifts, intensity variations, band disappearance, and the appearance of new vibrational features associated with structural reorganization and phase development. The reviewed studies demonstrate that thermal stability is primarily governed by octahedral composition, cation–OH bond strength, vacancy distribution, and crystallinity. Integration of spectroscopic observations with complementary diffraction and thermal analysis data provides a unified framework for understanding clay mineral transformations and for optimizing thermal processing in ceramic manufacture and calcined clay applications.

Ceramics doi: 10.3390/ceramics9080073

Authors: Chi-Yeung Mang Ka-Wai Yeung Tongqing Li Chi-Ho Wong Wing-Cheung Law Gary Chi-Pong Tsui Chak-Yin Tang

This study evaluates the rapid tooling feasibility and structural significance of utilizing digital light processing (DLP)-printed alumina as a near-net-shape ceramic mold-insert preform route for replication of curved polymer optics. While conventional production tooling for precision optics demands immediate optical-grade tolerances, the fundamental mechanisms governing polymer replication close to additively manufactured ceramic interfaces remain insufficiently understood. To isolate these multi-factor processing signatures, alumina specimens incorporating concave and convex parabolic surfaces were synthesized via lithography-based ceramic manufacturing. Our design acts as a geometric control lens, ensuring that thermal shrinkage trends, slicing kinematics, and interfacial replication behaviors are clearly exposed and quantified under uniform boundary conditions. Following debinding and sintering, exploratory hot-pressing cycles were executed to evaluate gross profile transfer and surface inheritance on poly(methyl methacrylate) (PMMA) replicas. Quantitative laser scanning confocal microscopy confirmed successful gross curvature generation and revealed geometry-dependent post-sintering shrinkage trends. The convex inserts exhibited an average peak-to-valley (PV) error of 123.48 ± 3.30 µm and an RMS error of 29.76 ± 1.23 µm, whereas the concave alumina inserts showed an average PV error of 137.98 ± 5.80 µm and an RMS error of 34.68 ± 1.20 µm. The PMMA replicas also showed substantial form deviation, with an average PV error of 163.72 ± 15.64 µm and RMS error of 27.37 ± 2.03 µm. Our work presents a route for producing near-net-shape ceramic mold-insert preforms that transforms complex processing variations into a predictable, mathematically addressable roadmap. A geometry-specific CAD pre-compensation can then be performed while the remaining precision gap can be selectively closed via targeted post-polishing depending on the desired optical application tier.

Ceramics doi: 10.3390/ceramics9070072

Authors: Benchalak Muangmeesri Sekporn Tansripraparsiri Sasithorn Khonthon Sirima Emwong Dechrit Maneetham

Thailand’s ceramic manufacturing tradition possesses a long and distinguished history, reflecting the nation’s rich cultural heritage, artistic excellence, and capacity for technological adaptation. Traditional Thai ceramics extend beyond their functional purposes, serving as important expressions of indigenous knowledge, craftsmanship, social values, and religious beliefs that have been transmitted across generations. While preserving their distinctive Thai characteristics, these ceramic traditions have continuously evolved through cultural exchanges with neighboring civilizations, particularly China and India, as well as later influences from the West. Among the various decorative techniques employed in Thai ceramics, stamping and hand-painted ornamentation are recognized as two of the most significant methods, contributing to the aesthetic and cultural value of ceramic works. These techniques enable ceramic products to embody both artistic expression and practical functionality by harmoniously integrating aesthetic design with reliable craftsmanship. In contemporary manufacturing environments, traditional stamping and painting methods are increasingly integrated with semi-automated processes and advanced ceramic machinery to enhance production efficiency while preserving cultural authenticity. This study proposes an Internet of Things (IoT)-based control system for ceramic stamping and painting machines, designed to support remote operation, real-time monitoring, and performance evaluation, with particular attention given to response time and error characteristics. By incorporating sensors, controllers, and networked communication technologies into ceramic manufacturing equipment, the proposed system establishes a meaningful connection between intelligent automation and traditional artistic practices.

Ceramics doi: 10.3390/ceramics9070071

Authors: Aleksandar Nikolov Mihail Tarassov Liliya Tsvetanova Zlatka Delcheva Nicolai Jordanov Nikolay Velinov Ivan Rostovsky

This study presents the development of a one-part phosphate-activated geopolymer foam based on fayalite flotation residue from the copper industry. The solid activator consisted of triple superphosphate, enabling a dry-mix binder that requires only water addition prior to use. Foamed materials were characterized by XRD, FTIR, Mössbauer spectroscopy, DSC-TG, hot-stage microscopy, SEM-EDX and physical and mechanical testing. The foaming of the geopolymer reduced the densities between 0.753 and 2.15 g/cm3, relative porosities up to 73.6%, and compressive strengths ranging from 1.4 to 28.8 MPa. The foamed geopolymer maintained dimensional stability up to about 1000 °C. The thermal conductivity coefficient measured on large-sized specimen blocks was 0.099 W/mK at a density of 0.753 g/cm3. These results demonstrate that fayalite slag can be effectively utilized as a precursor for sustainable geopolymer foams combining low thermal conductivity, high thermal stability, and the utilization of industrial by-products.

Ceramics doi: 10.3390/ceramics9070070

Authors: Seung-Hwan Son Seok-Hyeon Lee Kwang-Taek Hwang Jung-Hoon Choi Jin-Ho Kim Ung-Soo Kim Kyu-Sung Han

Silicon nanoparticles have attracted considerable attention as high-capacity anode materials for lithium ion batteries. However, the high specific surface area of nanoparticles results in excessive formation of the solid electrolyte interphase, leading to limitations in achieving high energy density. To overcome these limitations, pomegranate-shaped silica microparticles composed of aggregated silica nanoparticles were prepared using ultrasonic spray pyrolysis. Spherical silica nano sols with sizes ranging from 60 to 90 nm were employed as a precursor for the ultrasonic spray pyrolysis, yielding pomegranate-shaped silica microparticles. Subsequent magnesiothermic reduction and acid leaching converted silica into the silicon phase. The resulting silicon microparticles maintained a mean particle size of 2.37 μm with an average internal pore diameter of approximately 30 nm, preserving the structural morphology. Electrochemical evaluation revealed initial charge and discharge capacities of 3179 and 2416 mAh g−1, respectively. After 50 cycles, the discharge capacity stabilized at 500.9 mAh g−1.

Ceramics doi: 10.3390/ceramics9070069

Authors: Yuan Tu Jiawen Li Chaoyong Deng Min Zhang

A novel Dy3+-doped self-activated Sr2NaMg2V3O12 (SNMVO) phosphor was synthesized via a high-temperature solid-state reaction method. Its microstructure, surface morphology, valence state, and luminescence properties were investigated. The results showed that the prepared phosphor exhibited bright green emission at 521 nm and yellow emission at 575 nm under 345 nm excitation. The luminescence intensity showed a strong concentration dependence, with an optimal Dy3+ ion doping concentration of 0.05 mol, and the concentration quenching (CQ) mechanism was dipole–dipole (d-d) interaction. Energy transfer between vanadate and Dy3+ was observed, with a maximum transfer efficiency of 63.5%. The thermal activation energy (0.1859 eV) indicated good thermal stability. Furthermore, this phosphor can be used as a yellow phosphor for white light-emitting diodes (wLEDs) and for anti-counterfeiting patterns.

Ceramics doi: 10.3390/ceramics9070068

Authors: Dylan Vallet Philippe Michaud Yaasin Mayi Wen Zhang Vincent Pateloup

The shrinkage strain, occurring upon UV curing and aging, leads to non-uniform dimensional changes that can compromise the part’s final geometry. This study investigates the deformation of green parts during the stereolithography process. Based on experimental measurements, a finite element model (FEM) is developed to account for different phenomena contributing to the structural distortion of the part, like polymerization shrinkage and the adhesion between the part and the build platform during printing. In addition, the time dependency of the degree of conversion is also considered to integrate the aging of green parts, and elastoplastic material behavior is also considered to include non-reversible deformations. This novel model makes it possible to predict stress generation during the stereolithography process and simulate part warping over time. The resulting simulations provided a numerical validation for part shapes observed experimentally, as well as insights to better understand the deformation mechanisms and optimize the dimensional fidelity of stereolithography-manufactured components.

Ceramics doi: 10.3390/ceramics9070067

Authors: Chenxi Xia Min Xie Bianlei Hao Yonghe Zhang Congru Peng Lele Du Zhigang Wang Rende Mu Xiwen Song

Conventional 8YSZ thermal barrier ceramics suffer from limited phase stability and insufficient infrared radiation regulation at high temperatures. Sc2O3 doping can reduce thermal conductivity and improve phase stability, but the improvement remains limited because the fixed-valence substitution of Sc3+ cannot effectively increase defect concentration or regulate carrier behavior. In this work, CeO2 with tunable valence states was incorporated into the Sc-stabilized YSZ system to realize the synergistic modulation of lattice thermal conductivity and photon thermal conductivity. A series of Sc2O3–CeO2 co-doped YSZ ceramics were fabricated via solid-state sintering, and the effects of co-doping on phase structure, defect evolution, thermal conductivity, infrared emissivity, and bandgap characteristics were systematically investigated. The results show that all co-doped samples maintained a stable tetragonal fluorite structure with relative densities higher than 96%. Among them, Sc0.08Ce0.005Y0.005Zr0.91O2 exhibited the best comprehensive performance. Its thermal conductivity at 1000 °C reached 2.073 W·m−1·K−1, which was 11.9% lower than that of conventional 8YSZ. Meanwhile, the average infrared emissivity in the 3–5 μm band increased to 0.779. XPS analysis indicated that Ce incorporation promoted oxygen-vacancy formation, which enhanced phonon scattering and reduced lattice thermal conductivity. In addition, co-doping narrowed the band gap and facilitated carrier excitation, thereby strengthening infrared absorption and emission behavior. The enhanced infrared emissivity further contributed to the suppression of radiative thermal transport at elevated temperatures. This work demonstrates that Sc2O3–CeO2 co-doping provides an effective strategy for simultaneously regulating phonon transport and photon transport in YSZ-based ceramics. The results provide new insight into the design of advanced thermal barrier materials with low thermal conductivity and enhanced high-temperature infrared radiation performance.

Ceramics doi: 10.3390/ceramics9070066

Authors: Maja Kokunešoski Zivan Gojkovic Jovana Ružić

Clay, as a sediment material, is an attractive option for the production of porous ceramics due to its low price and high abundance. Porous ceramics possess a combination of essential properties of clay-based materials, including high porosity and thermal and chemical stability, making them suitable for various industrial applications, such as filters, heat insulators, and absorbents. In this study, thermally and chemically purified clay was mixed with boric acid as a pore-forming agent. Obtained results reveal that different contents of boric acid (2 wt.% and 0.5 wt.%) and variations in synthesis conditions, including low pressing pressures up to 60 MPa and low sintering temperatures of 1150 °C and 1300 °C, optimize the production of a filter medium with good separation and mechanical properties. Further, these findings indicate that an adequate combination of boric acid content and synthesis conditions positively affects mechanical properties, including values of hardness, Young’s modulus, compressive and tensile strength of clay-based filters. The clay-based filter with 2 wt.% boric acid exhibited a larger maximum pore diameter of nearly 0.2 mm, compared to the one with 0.5 wt.% boric acid. The filtering efficiencies of both filters were tested on pharmaceutical-grade ciprofloxacin with removal efficiency above 80% for two tested concentrations (6 μM and 9 μM).

Ceramics doi: 10.3390/ceramics9070065

Authors: Farid Lachibi Djamila Aboutaleb Cristina Siligardi Peter Futas Catrina Sgarlata Brahim Safi Alena Pribulová Mariusz Łucarz

This study aims to develop eco-efficient ceramic tiles through the valorization of recycled glass (GW; soda–lime glass cullet) as a partial raw material substituent, enabling a reduction in sintering temperature and, consequently, a decrease in thermal energy demand, carbon-equivalent emissions, and the depletion of virgin mineral resources. Ceramic tiles were elaborated by partially substituting natural bentonite with 30–50 wt.% GW and fired at 900 °C and 950 °C. Use of GW promoted liquid-phase sintering, driving significant densification evidenced by a marked reduction in open porosity and water absorption. SEM images confirm a denser, more homogeneous structure with reduced porosity, leading to improved mechanical strength and chemical durability. Compositions containing 30–35 wt.% bentonite exhibit the most optimized microstructure, characterized by well-dispersed crystalline phases embedded within a dense vitreous matrix. These findings demonstrate that high-performance ceramic tiles meeting standard classification thresholds can be manufactured at sub-1000 °C firing temperatures through judicious incorporation of recycled glass waste. This approach offers a viable pathway toward reduced energy consumption, diminished reliance on primary mineral resources, and enhanced circularity within the construction ceramics industry.

Ceramics doi: 10.3390/ceramics9070064

Authors: Akio Ikesue Yan Lin Aung

Hot isostatic pressing (HIP) was employed to fabricate 3 mol% Y2O3-stabilized ZrO2 ceramics with nearly pore-free microstructures. Zirconia ceramics containing residual pores (size: ~0.3 μm, <0.1%) exhibited a four-point bending strength of 1.11 GPa. In contrast, pore-free specimens achieved significantly higher strengths of 1.74 GPa for samples containing a small fraction of cubic grains and 2.29 GPa for specimens composed solely of the tetragonal phase. At the moment of fracture in the high-strength specimens, intense electrical discharges (visible sparks) were observed near the fracture origin. Post-fracture observations revealed that zirconia containing residual pores fractured into two pieces with relatively smooth fracture surfaces, whereas pore-free zirconia exhibited extensive fragmentation, producing highly irregular fracture surfaces. This behavior is likely associated with extensive rupture of Zr–O bonds within the crystal lattice during catastrophic fracture. These results demonstrate that the elimination of residual pores by HIP markedly enhances the attainable strength of zirconia ceramics and significantly alters their fracture behavior.

Ceramics doi: 10.3390/ceramics9060063

Authors: Yun Xu Weifu Cen

Ceramics, as a handicraft, is the crystallization of art and science. In order to study the firing process of ceramics, improve their density, mechanical properties, viscosity, and surface tension, and enhance the surface quality of the shaft, this article uses first-principles methods to study the electronic properties of ceramic colorants Al2O3, Fe2O3, TiO2, CaO, MgO, Na2O, KO2, and ceramic body SiO2. Research has shown that these seven color-developing agents exhibit anisotropy and have stable crystal structures. The bandgap values of Al2O3, CaO, Fe2O3, KO2, MgO, Na2O, TiO2, and ceramic SiO2 are 6.325 eV, 3.654 eV, 0 eV, 0 eV, 4.731 eV, 1.972 eV, 2.18 eV and 6.002 eV, respectively. In Al2O3/SiO2, Fe2O3/SiO2, TiO2/SiO2, CaO/SiO2, MgO/SiO2, Na2O/SiO2, and KO2/SiO2 systems, due to the influence of the potential field in the SiO2 system, the charge characteristics exhibit obvious interfacial and non-periodic characteristics. The research results revealed the charge transfer and distribution patterns at the interface between ceramic colorants and ceramic ligands, elucidating the influence mechanism of different colorants/embryo components on firing temperature, shrinkage rate, and finished product defects. This mechanism can be used to predict the advantages and disadvantages of alkali metals, iron, titanium, and aluminum components in raw materials, optimize low-temperature rapid firing formulas, suppress firing deformation, control pore defects, and improve the mechanical properties of finished products. It provides micro theoretical support for the industrialization, stabilization, and high-quality production of local ceramics in southwestern China.

Ceramics doi: 10.3390/ceramics9060062

Authors: Wenhao He Shaohua Su Bijun Fang Shuai Zhang Xiaolong Lu Jianning Ding

Lead-free [(Ba0.85Ca0.15)1−1.5xNdx][(Zr0.1Ti0.9)0.995Mn0.005]O3 (x mol% Nd/Mn BCZT, x = 0.05, 0.1, 0.5, 1 mol%) ceramics were prepared by the traditional solid-state reaction method, in which the synergistic effects of sintering temperature and Nd/Mn co-doping on the phase structure, microstructural evolution, and electrical properties were systematically investigated. All ceramics exhibit a pure perovskite structure, with the tetragonal (P4mm) phase dominating at room temperature as confirmed by the X-ray diffraction Rietveld refinement. The sintering temperature (1475–1520 °C) is found to be the primary factor governing densification and grain growth, with the relative density peaking at 91.7% for the x = 0.5 mol% sample sintered at 1505 °C. Within this optimized processing window, increasing the Nd content induces a gradual migration of the Curie temperature (TC) toward lower temperatures, accompanied by enhanced relaxor behavior. A highlight of this work is the strategic balance between piezoelectric activity and mechanical quality factor through a “donor–acceptor” co-doping mechanism. Specifically, for the x = 0.5 mol% ceramics, an exceptionally high mechanical quality factor (Qm = 424.5) is achieved for samples sintered at 1490 °C, which is proposed to be associated with the temperature-modulated formation of MnTi″−VO•• defect dipoles, while a peak inverse piezoelectric coefficient d33* of 685.1 pm/V is maintained at a sintering temperature of 1520 °C.

Ceramics doi: 10.3390/ceramics9060061

Authors: Wenxin Tan Ran Fu Yongjun Zhang Wenjuan Liang

Zirconia-toughened alumina (ZTA) ceramics are promising for load-bearing biomedical applications because they combine the hardness, chemical stability, wear resistance, and biocompatibility of alumina with the transformation-toughening capability of zirconia. Grinding is indispensable for achieving dimensional accuracy and surface quality, yet it inevitably introduces surface and subsurface cracks, residual stresses, and a local tetragonal-to-monoclinic transformation of zirconia. These changes can degrade fracture toughness, increase reliability scatter, and reduce long-term service stability. Annealing is therefore often considered a post-grinding recovery strategy because it can relax residual stresses, blunt crack tips, and partially restore the zirconia phase state. However, the extent of recovery depends strongly on the initial damage state, ZTA microstructure, and thermal schedule. This review systematically summarizes the current understanding of grinding-induced damage and annealing-assisted recovery in ZTA ceramics, with particular emphasis on the coupled relationships among subsurface damage, residual-stress evolution, phase transformation, and fracture toughness. Particular attention is given to distinguishing direct ZTA-specific evidence from mechanistic interpretations inferred from related zirconia-containing ceramic systems, because datasets based exclusively on ZTA remain relatively limited. By integrating the existing evidence, this review proposes a coupled processing-damage-recovery framework and identifies the key knowledge gaps that must be addressed to achieve more reliable process optimization in advanced ZTA components.

Ceramics doi: 10.3390/ceramics9060060

Authors: Bola Yoon James W. Klett Ryan M. Paul Michael J. Lance Hsin Wang Kashif Nawaz Edgar Lara-Curzio

Herein, we report a method to additively manufacture carbon fiber-reinforced siliconized silicon carbide composites. The process involves the pyrolysis of a 3D-printed carbon fiber-reinforced poly-ether-ether-ketone (PEEK) composite to produce a porous carbon fiber-reinforced carbon matrix composite preform, which is subsequently infiltrated with molten silicon to obtain a carbon fiber-reinforced siliconized silicon carbide composite. A key aspect of the method is limiting polymer melt flow during pyrolysis of PEEK, which is achieved by thermally annealing the 3D-printed carbon fiber-reinforced PEEK preform in air at a temperature below PEEK’s melting temperature. Rheological and differential scanning calorimetry (DSC) measurements demonstrate that the thermal annealing treatment altered the melting behavior of PEEK, while NMR and FTIR measurements provided a mechanistic explanation for the structural changes responsible for the behavior. It was also found that dimensional changes during pyrolysis were anisotropic with greater shrinkage in the stacking direction of the material.

Ceramics doi: 10.3390/ceramics9060059

Authors: Zahra Beladzar Djamila Boukhelkhal Mohamed Guendouz Seyed Mostafa Nouri Ilario Biblioteca Marco Valente

This study evaluates the durability of Self-Compacting Sand Concrete (SCSC) incorporating Windshield Glass Aggregate (WGA) as a sustainable replacement for natural sand, utilizing Blast Furnace Slag (BFS) as a constant filler component. Eleven mixtures were investigated: a control mix and ten variants with WGA substitution levels ranging from 10% to 100% in 10% increments. The specimens were exposed to elevated temperatures of 200–800 °C and to 240 freeze–thaw cycles between −18 °C and +9 °C. Under heating, mass loss increased with temperature, but WGA-rich mixtures generally showed lower mass loss and higher residual mechanical performance than the control. At 400 °C, WGA100 reached about 96 MPa in compressive strength and 15 MPa in flexural strength, corresponding to residual values of approximately 110.34% and 166.7%, respectively. After freeze–thaw cycling, all mixtures showed limited surface deterioration and mass loss below 1%, decreasing from about 0.76% for the control mixture to about 0.05% for WGA100. The improved durability is mainly attributed to the physical effect of WGA replacement and the baseline matrix refinement associated with BFS.

Ceramics doi: 10.3390/ceramics9060058

Authors: Zizheng Cai He Ma Kun Tian Feng Sun Lijuan Zhou Shuang Li

Sintering additives play a decisive role in the densification behavior, mechanical properties, and thermal conductivity of silicon nitride ceramics. In this study, Mg2Si and YH2 were used as sintering additives for gas pressure sintering of silicon nitride based on the synergistic mechanism of “silicide silicon extraction-hydride dehydrogenation”. The regulation rules of the additives on ceramic densification, mechanical properties, and thermal conductivity were systematically investigated. Two optimization strategies were proposed for the technical route of replacing traditional oxide additives with non-oxide systems. (i) Rare-earth hydride YH2 was used to replace traditional rare-earth oxides. It reacts with SiO2 to achieve strong deoxidation and precisely regulate the liquid phase composition. (ii) Metal silicide Mg2Si was used to replace metal oxides. It promotes the preferred growth of β-Si3N4 grains, consumes oxygen in the system, and reduces lattice defects. Mg2Si introduces Si into the liquid phase, increasing the Si/O ratio, which lowers lattice oxygen content and supports higher thermal conductivity. YH2 consumes SiO2 on the Si3N4 surface, which reduces liquid phase oxygen content and inhibits lattice oxygen incorporation, promoting a liquid phase with a high N/O ratio. Compared with traditional Y2O3, YH2 increases the Y2O3/SiO2 ratio in the liquid phase. It promotes grain growth, reduces SiO2 activity, and further improves the thermal conductivity of ceramics. Silicon nitride ceramics prepared by gas pressure sintering at 1750 °C with 3 wt.% Mg2Si and 4 wt.% YH2 composite additives exhibit the highest thermal conductivity of 87 W/(m·K), with a Vickers hardness of 14.36 GPa and a flexural strength of 643.15 MPa. This study provides an innovative idea for the preparation of high-performance silicon nitride heat dissipation substrates.

Ceramics doi: 10.3390/ceramics9060057

Authors: Štefan Csáki Tomáš Húlan Anton Trník Igor Štubňa

Samples made from illitic clay were investigated using thermogravimetry (TG), thermodilatometry (TD) and dynamic mechanical analysis (DMA) during heating from room temperature to 300 °C. TG revealed three steps of mass loss: (a) the release of weakly bound H2O (with the maximum rate at ~120 °C) from the pores, (b) a small mass loss event around 215 °C, (c) a small mass loss event near ~300 °C related to dehydration when H2O molecules located in K-free sites of the illite interlayers are removed. TD indicated very small dimension changes for 20 °C → 300 °C. This behavior may result from two competing mechanisms, where the first one is regular thermal expansion and the second one is particle rearrangement caused by the removal of physically bound water. Young’s modulus initially decreases during heating up to approximately 70 °C. Young’s modulus subsequently increases exponentially, which may be explained by mechanisms analogous to those observed in the TD measurements. The activation energies derived from the exponential dependence E(t) are 5.66 kJ/mol for the temperature interval 130–200 °C and 10.96 kJ/mol for the 200–280 °C range.

Ceramics doi: 10.3390/ceramics9060056

Authors: Zhiyong Yang Shengxian Luo An Xue Fangfang Zeng Yang Liao Yang Li Zhiyao Chu Qibin Liu Huaizhang Gu

Lead-free piezoelectric ceramics have attracted substantial attention in environmental protection and energy storage applications due to their excellent performance. In this study, the Ba1−xCaxZr0.1Ti0.9−ySnyO3(BCZTS) lead-free piezoelectric ceramic system was synthesized. The effects of doping ratios of Ca and Sn, as well as sintering temperature, were systematically investigated on the phase structure, microstructure, and piezoelectric properties of BCZTS ceramics. The results showed that the Ba0.88Ca0.12Zr0.1Ti0.81Sn0.09 ceramics synthesized with a Ca doping content of x = 12 mol% and a Sn doping content of y = 9 mol % had a homogeneous phase structure with an Orthorhombic–Tetragonal (O-T) morphotropic phase boundary (MPB) and uniform grain size. At a sintering temperature of 1300 °C, the ceramics achieved optimal piezoelectric performance, with a piezoelectric coefficient d33 = 319 pC/N. These lead-free piezoelectric ceramics have superior properties compared to conventional lead-based piezoelectric ceramics in the local market, providing a novel and feasible way to replace lead-based ones in civilian applications.

Ceramics doi: 10.3390/ceramics9060055

Authors: José Adalberto Castillo-Robles Rubí Maria Cobos-Ramos Jesús Emmanuel López-Zúñiga Eddie Nahúm Armendáriz-Mireles Enrique Rocha-Rangel

This work reports the synthesis, characterization, and photocatalytic performance of multifunctional spheres based on AgNP-doped TiO2-Fe3O4 embedded in an alginate–chitosan biopolymeric matrix for the removal of organic contaminants from water. The composite powders exhibited a nanocrystalline structure composed of anatase TiO2 (~20 nm) and magnetite (~25 nm), with homogeneously dispersed Ag nanoparticles, as observed by SEM. The spheres presented a mainly submicrometric particle size distribution (0.55–0.92 µm), favoring high surface area and colloidal stability. Under simulated solar irradiation, the material achieved efficient photocatalytic degradation of methylene blue, with a pseudo-first-order rate constant of 0.112 h−1 and ~46% decolorization after 5 h. UV-Vis spectra showed progressive attenuation of the dye absorption band without accumulation of intermediates. Magnetic recovery tests confirmed rapid separation and reuse without performance loss. The enhanced activity is attributed to the synergistic interaction among plasmonic Ag, photocatalytic TiO2, redox-active Fe3O4, and the adsorptive carbon–biopolymer matrix. The material exhibited strong antibacterial activity, achieving over 90% removal of fecal coliforms after 5 h of irradiation. Therefore, the developed AgNP-doped TiO2-Fe3O4 spheres represent a sustainable, reusable, and efficient material for solar-assisted water sanitation.

Ceramics doi: 10.3390/ceramics9060054

Authors: Saken Uderbayev Aizhan Dilmanova Aigerim Khamit Gulnaz Zhakapbayeva Akmaral Zhapakhova Nargul Saktaganova Koktem Yerimbetov

This study investigates the development of sustainable ceramic materials using industrial and agricultural waste from the Kyzylorda region of Kazakhstan. The research focuses on the combined use of local clay, ash from the Kyzylorda thermal power plant (TPP), and rice husk ash (RHA). Experimental investigations included the evaluation of chemical composition, linear and volumetric shrinkage, water absorption, bulk density, and compressive strength of ceramic samples fired at 950–1050 °C. Microstructural (SEM) and phase composition (XRD) analyses were performed to explain the observed behavior. The results showed that the optimal composition was 70% clay, 20% TPP ash, and 10% RHA, which demonstrated the highest compressive strength (15.45 MPa), reduced water absorption, and improved densification. The enhanced performance is attributed to partial vitrification and viscous-phase-assisted densification and the formation of crystalline phases such as mullite, cristobalite, and anorthite. The study confirms that the combined use of TPP ash and RHA enables effective recycling of local waste materials and improves the physical and mechanical properties of ceramic products.

Ceramics doi: 10.3390/ceramics9060053

Authors: Davide Casotti Erika Iveth Cedillo-González Cristina Siligardi

The ceramic tile industry is increasingly required to reduce its environmental impact while maintaining high technological and aesthetic standards. In this context, the use of secondary raw materials (SRMs) represents a promising strategy to decrease the consumption of virgin resources and the energy demand associated with conventional frit production. At the same time, solar-reflective engobes can contribute to passive cooling by limiting solar heat absorption and mitigating the urban heat island effect. In this study, white solar-reflective engobes were developed by incorporating at least 8 wt.% of SRMs, including various recycled glass streams, ceramic wastes, and yttria-stabilized zirconia residues. The results demonstrate that optimized formulations achieve high solar reflectance values (up to 0.79) while maintaining the technological and aesthetic requirements of industrial ceramic tiles. Recycled glasses act as effective fluxing agents, whereas waste zirconia enhances optical performance due to its strong light-scattering capability. The most promising formulations were validated at the industrial scale, confirming their applicability under real production conditions. Overall, the developed engobes represent a scalable alternative to traditional frit-based systems, enabling reduced resource consumption and supporting the development of energy-efficient ceramic surfaces.

Ceramics doi: 10.3390/ceramics9050052

Authors: Roman Aleksandrovich Shishkin

Thermal barrier coatings (TBCs) require materials with intrinsically low thermal conductivity and high grain-boundary thermal resistance to maximize the temperature gradient across the top coat. In this work, the effective thermal conductivity of more than 40 prospective TBC oxides belonging to seven structural families (YSZ/YSH, pyrochlores/fluorites A2B2O7, defective fluorites A3BO7, fergusonite/monazite ABO4, and perovskites ABO3) was systematically deconvoluted into intrinsic grain thermal conductivity (kgrain) and grain-boundary (Rgb) contributions. It is shown that grain-boundary Kapitza resistance dominates heat transport in virtually all advanced oxides, contributing 60–90% to the total thermal resistance of polycrystalline samples. The lowest kgrain values (4–12 W m−1 K−1) are found for cerates and certain tantalates, while the highest Rgb (up to 7.2 × 10−6 m2 K W−1) are characteristic of high-entropy and heavily doped perovskites. Orthorhombically distorted SrCeO3-based and high-entropy perovskites combine moderate kgrain (4.7–27.9 W m−1 K−1), high Rgb, and tunable thermal-expansion coefficients (10–13 × 10−6 K−1), making them the most promising candidates for next-generation TBCs. These findings provide a rational basis for microstructure engineering and composition design aimed at maximizing the temperature drop across TBC layers while maintaining phase stability and CMAS resistance.

Ceramics doi: 10.3390/ceramics9050051

Authors: Weimin Luo Mingder Jean

This study centred on the parametric optimisation and performance prediction of NiCr/WC-Co coatings produced by high-velocity oxygen fuel (HVOF) spraying. An L18 orthogonal experimental design based on the Taguchi method and the response surface method (RSM) was adopted to examine how key process parameters affect the microstructure, phase composition and hardness of the coatings. The results revealed that analysis of variance (ANOVA) indicated that travel speed, methane flow rate, powder feed rate, and stand-off distance were the primary parameters affecting coating hardness, collectively accounting for 76.25% of the total variance. Also, the RSM model established in this study demonstrates remarkably high predictive accuracy, with a coefficient of determination (R2) of 0.985 and an average prediction error of just 1.16%. Verification experiments were also conducted under optimal conditions. The measured hardness was 1352.7 ± 75 HV, in close agreement with the predicted value of 1365 HV. The coating, which was applied using HVOF spraying, had a dense layered structure and low porosity, and the decarburisation of the tungsten carbide was extremely minimal. In addition, interfacial bonding is improved and structural defects are reduced by the addition of a NiCr intermediate layer. It is demonstrated by the results that the Taguchi-RSM method is reliable for the optimization of HVOF spraying parameters and the prediction of coating hardness.

Ceramics doi: 10.3390/ceramics9050050

Authors: Sohaib Fadhil Mohammed Mohd Firdaus Yhaya Matheel Al-Rawas Tahir Yusuf Noorani

The use of zirconia as a material in the base of modern restorative dentistry is due to its high strength, biocompatibility, and improved aesthetic performance. The aim of this review is to provide an integrated and coherent overview of the recent developments in zirconia crowns by focusing on the development of materials, microstructure, digital fabrication processes, optical capabilities, and clinical performance. A survey of literature in the form of a narrative literature review was conducted in the most significant databases, such as PubMed, Scopus, Web of Science, and Google Scholar, including publications published since 2000, with a focus on systematic reviews, meta-analyses, clinical studies, and materials science studies. The results show that zirconia materials have developed beyond traditional 3Y-TZP systems, characterized by high strength and fracture toughness to high-translucency and multilayer zirconia (4Y 6Y-PSZ) systems, which provide better aesthetics at the cost of lower mechanical reliability. The implementation of CAD/CAM technologies has enhanced the accuracy of fabrication, marginal fit and reproducibility and the development of sintering, surface modification and bonding protocols has enhanced clinical performance. Recent clinical results have shown high survival rates (around 85–95 percent over 5–10 years), and the results depend on the design of the restoration, the zirconia generation, and the functional loading circumstances. Despite these developments, there are still concerns about the durability of bonding, trade-offs between translucency and strength, and long-term performance of high-translucency zirconia. The development of new technologies, such as additive manufacturing, design-aided artificial intelligence, and bioactive surface modification, is a promising avenue toward improving clinical reliability and performance.

Ceramics doi: 10.3390/ceramics9050049

Authors: Akio Ikesue Yan Lin Aung

Fully dense monoclinic zirconia ceramics were successfully fabricated by pressureless sintering and/or HIP. Although monoclinic zirconia exhibits unique physicochemical properties, fabrication of fully dense polycrystalline bodies has remained challenging due to catastrophic volume expansion during the tetragonal-to-monoclinic transformation. By introducing a synergistic ternary (Ga2O3-ZnO-TiO2) sintering aid, a relative density exceeding 99.6% with an average grain size of 0.5–2 µm was achieved by sintering under an oxygen atmosphere at 1070 °C for 3–100 h, well below the phase-transition temperature. X-ray diffractometry confirmed a single-phase monoclinic structure. Subsequent hot isostatic pressing at 1080 °C and 180 MPa for 2 h eliminated residual porosity, yielding a 4-point bending strength of 328 MPa, a fracture toughness of 2.7 MPa·m0.5, and a Vickers hardness HV1 of 805. This monoclinic zirconia ceramic exhibited ~30% total transmittance, while in-line transmittance remained below 0.1% due to intrinsic birefringence of the monoclinic lattice. These results established a low-temperature route for densifying phase-sensitive ceramics while achieving long-term stability.

Ceramics doi: 10.3390/ceramics9050048

Authors: Mahesh Kumar Munchikana Shivakumar Jagadish Shetty Anbukkarasi Rajendran Gurumurthy Sangam Chandrashekar Manjunath Shetty Tarun Sharda Raghavendra Karkala Gururaj

The structural response of ceramics to extreme deformation is of significant scientific and technological relevance since such conditions are commonly encountered during both processing and service. In this study, monoclinic zirconia was subjected to high-energy ball milling for extended durations of 80 h and 120 h, followed by annealing at 1000 °C. X-ray diffraction revealed a progressive increase in the tetragonal phase content with milling duration, while subsequent annealing promoted its consolidation alongside the principal monoclinic phase, resulting in a stable biphasic structure. The phase evolution is also evaluated through a Raman spectroscopy analysis and correlated with the morphology, mechanical properties, and surface area analyses. Scanning electron microscopy confirmed the preservation of nanoscale features in the milled and annealed specimens, in contrast to the unmilled sample, which exhibited pronounced grain coarsening. The combined presence of nanostructural stability and biphasic phase constitution underscores the efficacy of high-energy ball milling, in conjunction with thermal treatment, as an effective strategy to tailor the microstructure and phase stability of zirconia ceramics for advanced engineering applications.

Ceramics doi: 10.3390/ceramics9050047

Authors: Andrey V. Poligenko Evgeny A. Ruban Kirill M. Osipov Andrey A. Shaporenkov Vladimir V. Dushik

In this study, a multiphysics finite-element model was developed for the deposition of W–C–B coatings in a hot-wall tubular CVD reactor from a gas mixture of tungsten hexafluoride (WF6), hydrogen (H2), and trimethylamine borane ((CH3)3N:BH3) at 550 °C and 5 Torr. The aim of this work is to deepen the understanding of reactant transport mechanisms and to optimize the process parameters for obtaining targeted tungsten carbide or boride phases. The simulations were performed in COMSOL Multiphysics (ver. 6.1) using a 2D axisymmetric formulation that couples laminar flow, heat transfer, and multicomponent diffusion, accounting for heterogeneous chemical reactions at the reactor walls. The obtained spatial distributions of reactant concentrations demonstrate precursor depletion along the reactor length. A comparison of the calculated B/W and C/W stoichiometric ratios for 13 operating conditions with experimental data confirms a transition from W and W–B phases at low trimethylamine borane (TMAB) flow rates to tungsten carbide-based coatings at higher flow rates. Furthermore, a parametric sweep was utilized to determine the optimal parameter range for the synthesis of tungsten borides.

Ceramics doi: 10.3390/ceramics9050046

Authors: Mohammod Hafizur Rahman

Ceramic membranes show potential for high-temperature CO2 extraction from flue gas; nevertheless, their performance under simultaneous heat and pressure stress is not well comprehended. This research addresses the temperature-dependent CO2/N2 separation characteristics of a commercial ceramic membrane (pore size ~0.1–1 µm) utilizing simulated flue gas (11.8% CO2, 74.2% N2, 2.5% O2, remainder CH4) at temperatures ranging from 60 to 140 °C and pressures between 4 and 6 bar. Calibrated GC-TCD was used to quantify permeate compositions across multiple operating valve openings. With a CO2/N2 selectivity (α) of 0.75 at 4 bars, the maximum CO2 enrichment peaked at 80 °C (10.8 mol%), getting close to the Knudsen diffusion limit (0.80). Selectivity decreased dramatically beyond 100 °C—α = 0.61 (100 °C), 0.45 (140 °C)—and CO2 dropped to 5.8% at 4 bar and 2.2% at 6 bars. Viscous flow dominance was shown by the strong pressure amplification—α decreased by more than 60% from 4 to 6 bar at all temperatures. These findings emphasize the possibility of performance collapse in hot, pressured flue streams and identify the limited operating window under which Knudsen-controlled transport can be maintained. The study provides quantitative evidence of a transition in transport regime under mixed flue-gas conditions.

Ceramics doi: 10.3390/ceramics9050045

Authors: Zhuo Chen Peng He Yueyue Wang Qingqing Zhou Feng Tao Qi Liu Yuexin Liu

MXenes, with a high surface area, abundant active sites, and excellent ion transport properties, have demonstrated excellent electrochemical performance. However, systematic comparisons of the structural evolution process and electrochemical performance for MXene are lacking. In this study, multilayer MXene (M-Ti3C2Tx) was successfully fabricated by in situ etching. During the subsequent centrifugation process, the thicker and heavier multilayer sheets settled due to their faster sedimentation rate, while the lighter, surface-functionalized monolayer sheets remained colloidally stable in the supernatant due to solvation and electrostatic repulsion, thereby achieving separation and obtaining delaminated MXene (D-Ti3C2Tx). Structural analysis indicates that the removal of the aluminum layer synergizes with the exfoliation of the nanosheets, significantly increasing the interlayer spacing and making the sheet structure more pronounced, and the pore structure is more abundant. Especially, in three-electrode and two-electrode systems at an identical mass loading of 5 mg on carbon paper, D-Ti3C2Tx delivered a higher specific capacitance, more pronounced pseudocapacitive behavior, and a superior rate capability compared to Ti3AlC2 and M-Ti3C2Tx. Such excellent electrochemical performance of D-Ti3C2Tx is due to the shortened ion diffusion path in the delaminated structure, which enables rapid ion migration, an extremely large specific surface area, and a mesoporous structure that provides abundant active sites. This study underscores the significant potential of D-Ti3C2Tx in emerging energy storage systems and offers insights into guiding MAX phase synthesis during its preparation.

Ceramics doi: 10.3390/ceramics9050044

Authors: Zaeem Ur Rehman Muhammad Faheem Maqsood Mohsin Ali Raza Syed Muhammad Zain Mehdi Rumasa Kanwal Umair Azhar Sunil Kumar Muhammad Javaid Iqbal Waseem Amin Muhammad Farooq Khan Sharafat Ali

The effect of A-site substitution on the morphological and electrochemical properties of La1-xSrxMnO3 (x = 0, 0.25, 0.50) perovskites was investigated to evaluate their potential as electrode materials for supercapacitors. X-ray diffraction analysis confirmed the formation of the perovskite structure, with minor peak shifts and distortion of crystal structure induced by Sr substitution. Scanning electron microscopy analysis revealed irregularly shaped particulate morphology across all perovskite compositions. The increasing amount of Sr as in La0.5Sr0.5MnO3 (LSM-50) favored the formation of nanosized particles, and energy dispersive X-ray (EDX) analysis confirmed the presence of all constituent elements; EDX elemental mapping also showed a uniform distribution of all elements in the various perovskite compositions. Among all compositions, La0.75Sr0.25MnO3 (LSM-25) possessed the highest specific capacitance (Csp) of 483 Fg−1 at 1 Ag−1 current density in 3 M KOH electrolyte, as determined by electrochemical analysis. This perovskite material also exhibited a capacitance retention of 87.8% after 5000 charge–discharge cycles. Electrochemical impedance spectroscopy revealed that LSM-25 showed the lowest solution resistance (0.68 Ω*cm2) and charge transfer resistance (1.52 Ω*cm2), indicating strong electrode–electrolyte interaction. Detailed analysis of cyclic voltammetry data revealed that the predominant charge storage mechanism was diffusive in nature, with 88% of the diffusive contribution registered for LSM-25. These findings demonstrate that Sr substitution at the A-site significantly enhances the energy storage performance of LaMnO3, making it a promising candidate for supercapacitor applications.

Ceramics doi: 10.3390/ceramics9050043

Authors: Subin Antony Jose John Crosby Pradeep L. Menezes

Ceramics are widely evaluated for their extreme hardness, high-temperature stability, and corrosion resistance, which enable applications in harsh service environments. However, these same properties, high melting points, brittleness, and low thermal shock resistance, make conventional manufacturing of complex ceramic components difficult and expensive. Traditional processes often require costly diamond tooling or energy-intensive sintering and tend to produce only simple geometries, with significant waste material and risk of defects. Additive manufacturing (AM) has recently emerged as a promising route to fabricate intricate, near-net-shape ceramic parts without these drawbacks. By building components layer by layer, AM reduces the need for extensive machining and enables the fabrication of geometrically complex, near-net-shape ceramic structures with reduced material waste, although challenges such as porosity, interlayer defects, and cracking during post-processing remain. Nonetheless, ceramic AM technologies lag behind their metal and polymer counterparts, and significant challenges remain in achieving fully dense parts with reliable mechanical properties. This review provides an in-depth overview of the state of the art in ceramics and ceramic composite additive manufacturing. We detail the most widely used AM processes (stereolithography, binder jetting, material extrusion, powder bed fusion, inkjet printing, and direct energy deposition) and typical feedstock formulations for each technique. We examine the resulting mechanical properties (strength, toughness, hardness, wear resistance) and functional properties (thermal stability, dielectric behavior, biocompatibility) of additively manufactured ceramics, and discuss their current and potential engineering applications in the aerospace, defense, automotive, biomedical, and energy sectors. Persistent challenges, including porosity, shrinkage and cracking during sintering, achieving uniform microstructures, high process costs, and scalability issues, are analyzed, and we highlight promising future directions such as multi-material grading, integration of machine learning for process optimization, and sustainable manufacturing approaches. Despite significant progress, challenges remain in achieving fully dense structures, improving process reliability, and scaling ceramic AM for industrial applications, highlighting the need for further research in process optimization, material design, and multi-material integration.

Ceramics doi: 10.3390/ceramics9040042

Authors: Stevan Stojadinović Darwin Augusto Torres-Ceron Sebastian Amaya-Roncancio Nenad Radić

Porous, crystalline gamma-Al2O3 coatings with a thickness of (6 ± 0.5) μm and a uniform distribution of rare earth (RE) dopants are synthesized by plasma electrolytic oxidation of aluminum at a current density of 150 mA/cm2 in a boric acid and borax (BB) solution containing added RE oxide particles (Ho2O3, Tb4O7, and Pr6O11) at concentrations of 1, 2, and 4 g/L. The concentration of RE oxide particles in the BB solution determines the amount of RE elements incorporated into the coatings but does not significantly affect their surface morphology, crystal structure, or light absorption properties. The coatings exhibit high absorption in the middle/near-ultraviolet region, characteristic of Al2O3. Typical 4f-4f transitions of Ho3+, Tb3+, and Pr3+ are observed in the photoluminescence spectra. Photocatalytic evaluations using methyl orange degradation under simulated solar irradiation show that RE doping significantly enhances photocatalytic efficiency. Peak degradation efficiencies are achieved at a concentration of 4 g/L for all RE oxides. After 8 h of irradiation, maximum degradation reaches 88%, 92%, and 85% with pseudo-first-order rate constants (kapp) of about 0.274 h−1, 0.339 h−1, and 0.232 h−1 for coatings synthesized in BB with 4 g/L Ho2O3, Tb4O7, or Pr6O11, respectively. In comparison, the pristine Al2O3 coating achieves only about 50% degradation (kapp ≈ 0.087 h−1). Photoluminescence indicates that RE3+ ions serve as effective charge-carrier traps, suppressing electron–hole pair recombination. RE-doped Al2O3 coatings demonstrate exceptional structural stability and reusability over six cycles, highlighting their potential for sustainable wastewater remediation.

Ceramics doi: 10.3390/ceramics9040041

Authors: Malika Saâdaoui

Engineering ceramics are successfully used as structural or functional materials in a wide range of technical and biomedical applications [...]

Ceramics doi: 10.3390/ceramics9040040

Authors: Shuxin Liu Xinglian Song Changchun Wang Wenju Liao Zhen Wang Haomiao Yu

The traditional solid-state method was employed in this study to prepare Mn-Zn ferrite. By adjusting the sintering temperature and the MoO3 doping ratio, the evolution of its structural and magnetic properties was systematically investigated. Fe2O3, MnO, and ZnO were used as the main raw materials, with MoO3 serving as an additive. MoO3 was doped at molar ratios ranging from 0 to 1000 ppm under experimental conditions involving a sintering temperature between 1125 °C and 1165 °C and an oxygen concentration of 1.5%. The addition of an appropriate amount of MoO3 led to an increase in the Q value, which consequently resulted in a reduction in the loss. The formation of a single-phase spinel structure was confirmed by X-ray diffraction analysis. Observations of the surface morphology revealed that the grain size also increased with the increase in MoO3 content, a trend consistent with the enhanced grain growth kinetics at higher MoO3 levels. In this study, a Mn-Zn ferrite material with excellent comprehensive performance was successfully prepared under the optimal conditions of a sintering temperature of 1150 °C and a MoO3 doping concentration of 500 ppm. A Q value of 22.3 was obtained for this material at 25 °C, while a Q value of 15.7 was obtained at 100 °C. At room temperature, a Q value of 192.4 was measured at a test frequency of 500 kHz, and a Q value of 137.2 was measured at 1 MHz. At a frequency of 500 kHz, a loss of 27.1 kW/m3 was observed at 25 °C, and a loss of 53.6 kW/m3 was observed at 100 °C. At a frequency of 1 MHz, a loss of 88.2 kW/m3 was recorded at 25 °C, while a loss of 183.7 kW/m3 was recorded at 100 °C. Additionally, the lattice constant was stabilized in the range of 8.52–8.53 Å, indicating favorable structural stability.

Ceramics doi: 10.3390/ceramics9040039

Authors: Alfredo Aguilar-Elguezabal Armando Reyes-Rojas Hilda Esperanza Esparza-Ponce Daniel Lardizábal-Gutiérrez Miguel Humberto Bocanegra-Bernal

Ceramic materials are indispensable to aerospace and defence technologies, where structural and functional components are required to withstand extreme thermal, mechanical, and chemically aggressive environments. Traditionally valued for their exceptional thermal stability, oxidation resistance, and corrosion resistance, ceramics have nonetheless been constrained by their inherent brittleness, which has limited their widespread adoption in load-bearing structural applications. This review surveys the principal tough ceramic systems currently employed in aerospace and defence, including SiC, Al2O3, ZrO2, Si3N4, SiC/SiC composites, and ultra-high-temperature ceramics (UHTCs) such as ZrB2 and HfB2. In parallel, it outlines advanced processing and manufacturing routes that enable enhanced microstructural control, improved reliability, and scalability for industrial deployment. Special attention is devoted to thermal and environmental barrier coatings (TBCs and EBCs), which provide critical protection against oxidation, corrosion, and severe thermal cycling in propulsion, power-generation, and hypersonic systems. Finally, the review highlights key material selection criteria for aerospace and defence platforms and discusses emerging trends that integrate tough ceramics with next-generation manufacturing technologies, underscoring their pivotal role in enabling high-performance, durable, and resilient systems for future extreme-environment applications.

Ceramics doi: 10.3390/ceramics9040038

Authors: Daniela Gier Della Rocca Victor de Aguiar Pedott Fernanda Cristina Fraga Adriano da Silva Rosely Aparecida Peralta Enrique Rodríguez-Castellón Natália Ueda Yamaguchi Bruno Francisco Oechsler Regina de Fátima Peralta Muniz Moreira

Membrane technology is a highly efficient, cost-effective, and chemical-free process, leading to its widespread application across various fields. However, the high capital cost of traditional ceramic benchmarks remains a barrier. This study addresses this challenge by engineering a low-cost, waste-derived geopolymeric membrane functionalized with a silver molybdate (Ag2MoO4) catalytic coating for the removal of trimethoprim (TMP), a persistent emerging contaminant. Systematic filtration assays for the removal of TMP (100 mg·L−1, pH 4) revealed the role of the Ag2MoO4 layer as a performance intensifier, yielding a 26% increase in initial permeate flux and a 33% improvement in the selectivity compared to the pristine support, while maintaining robust rejection efficiency. Comprehensive characterization attributes these enhancements to synergistic effects between increased surface hydrophilicity and favorable solute–catalyst interfacial interactions. Furthermore, a fouling analysis using Hermia’s models indicated the simultaneous operation of multiple blocking mechanisms, a phenomenon linked to the non-uniform nature of the coating and subsequent formation of preferential flow paths. Overall, the incorporation of the silver molybdate coating effectively improved the membrane’s flux performance and selectivity. These findings demonstrate that integrating catalytic coatings onto waste-based geopolymer frameworks provides a scalable, circular-economy-aligned strategy for advanced wastewater treatment, balancing high-flux performance with the efficient removal of recalcitrant pharmaceuticals.

Ceramics doi: 10.3390/ceramics9040037

Authors: Chaochen Chen Fang Lei Shiqing Dang Hongyang Zhang Ying Shi Haohong Chen

To address the lack of suitable glass systems for silicon nitride (Si3N4) surface metallization, which requires high wettability and thermal stability, and robust bonding between the copper layer and the ceramic substrate, a novel Bi2O3-TeO2-B2O3-CuO glass system was developed. This study systematically investigated the influence of Bi2O3 concentration, glass properties, optimized paste composition, and brazing mechanism using phase analysis, microstructural characterization, particle size statistics, thermal analysis, and tensile testing. An optimal glass composition containing 20 mol% Bi2O3 was identified, exhibiting high thermal stability (ΔT = 224 °C) and a coefficient of thermal expansion of 9.63 × 10−6 °C−1. At a brazing temperature of 750 °C, the glass demonstrated excellent wettability with a contact angle of 27°. A conductive paste comprising 94 wt% Cu and 6 wt% glass yielded a thick film with a minimum resistivity of 6.25 μΩ·cm and a maximum tensile strength of 25.2 MPa. Mechanism analysis revealed that the superior wettability drives the liquid glass phase to form a thin intermediate layer that significantly reinforces adhesion. These findings contribute to the research and development of subsequent novel glass systems with superior performance.

Ceramics doi: 10.3390/ceramics9040036

Authors: Carlos Andres Cardenas Balaguera Andres Felipe Rubiano-Navarrete Pilar Astrid Ramos Casas Lina Paola Espitia López

The research focuses on the development of chemically bonded phosphate ceramics using potassium hydrophosphate and steel slag (EAF) as raw materials. The objective is to scale up the laboratory results to design a ceramic paste suitable for architectural monolithic products, promoting the recycling of EAF steel slag. The methodology includes field visits, grinding and sieving of raw materials, and the fabrication of specimens following ASTM standards. The laboratory results from existing studies on multiphase phosphate cements from steel slags indicate that exothermic reactions and the increase in reactants can affect process scaling. Furthermore, shaping methods such as casting and pressing are evaluated, where pressing proves to be the most suitable for this type of phosphate cement as it increases the material’s mechanical properties (compressive strength), reduces porosity, and generates a greater utilization of the EAF steel slag residue. Taking into account Colombian technical standards regarding the minimum compressive strength that a monolithic architectural object must withstand for structural and non-structural use, the results obtained in this research allow us to conclude that this material can indeed be used for architectural purposes.

Ceramics doi: 10.3390/ceramics9030035

Authors: Aime Gutiérrez Peralta Fernando Daniel Cortés Vega Susana Meraz Dávila

This work investigates the effect of high-energy mechanical milling on the activation and phase transformation of synthetic pseudoboehmite powders. The approach aims to provide a clean, solvent-free route with potential industrial relevance for alumina production. Mechanical processing proved effective in inducing the transition from pseudoboehmite to χ-Al2O3 solely through milling. The process yielded nanometric particles with low levels of contamination. The subsequent conversion to α-Al2O3 was achieved through controlled heat treatments, while phase evolution was monitored by differential scanning calorimetry (DSC). A reduction of approximately 110 °C in the α-Al2O3 formation temperature was observed after 30 h of milling. This shift was accompanied by a marked decrease in the activation energy, from 526 kJ·mol−1 for the raw powder to 347 kJ·mol−1 for the milled sample. These results demonstrate the strong mechanochemical activation of pseudoboehmite, highlighting mechanical milling as an effective and scalable route for energy-efficient processing of alumina phases.

Ceramics doi: 10.3390/ceramics9030034

Authors: Pedro Henrique Poubel Mendonça da Silveira Ary Machado de Azevedo Marcelo Henrique Prado da Silva

Hydroxyapatite (HAp) is a key bioceramic for biomedical applications, but conventional pressureless sintering (PS) requires high temperatures that can promote phase degradation. Here, we compare PS (1100 °C/180 min) and cold sintering process (CSP) (150 °C/450 MPa/30 min) for pure HAp and an HAp composite containing 4 wt.% niobium–phosphate bioglass (BG), using a 2 M H3PO4 transient liquid (10 wt.%). CSP increased relative density from 73.10% to 79.92% for HAp and from 68.43% to 83.54% for HAp/BG, representing up to a 22.1% gain compared with PS. One-way ANOVA confirmed a significant effect of processing route/composition on relative density (F(3,24) = 919.69, p < 0.05), and Tukey HSD indicated that all groups differed statistically. SEM revealed a markedly more consolidated and homogeneous microstructure for CSP, particularly for HAp/BG, consistent with enhanced dissolution–reprecipitation and pore filling. XRD showed that PS at 1100 °C led to partial HAp degradation with β-TCP formation, whereas CSP preserved the HAp phase with broader peaks, smaller crystallite size, and higher specific surface area. These results demonstrate CSP as an efficient low-temperature alternative for densifying HAp-based bioceramics, with BG addition further improving consolidation.

Ceramics doi: 10.3390/ceramics9030033

Authors: Amina Benatia Najwa Gouitaa Ina Turcan Felicia Gheorghiu Laura-Elena Ursu Liviu Leontie Liliana Mitoseriu Fatima Zahra Ahjyaje Taj-dine Lamcharfi Farid Abdi

This research aims to investigate the modifications of the structural, dielectric, and sensing properties of CaFeO3−δ ceramics produced by solid-state reaction induced by varying sintering temperatures in the range of 1000–1200 °C. A single crystallographic orthorhombic (Pcmn) structure was revealed by X-ray diffraction with Rietveld analysis, both for the powders and sintered ceramics, irrespective of the sintering temperature. The increase in the sintering temperature induces better densification and a larger grain size. Dielectric measurements reveal a pronounced enhancement of the relative permittivity, reaching 2 × 105 at 1 kHz and 330 °C for the sample sintered at 1200 °C/4 h. This composition also displays the highest electrical conductivity, 0.4 S/m at 1 MHz. Cole–Cole analysis indicates a clear deviation from ideal Debye behavior, while the relaxational features of the dielectric permittivity suggest a strong correlation between the dielectric response and Fe-related conduction mechanisms. Gas sensing tests show that the ferrite ceramics exhibit consistent ethanol response trends. The ceramic sintered at 1200 °C/4 h achieved the highest sensitivity, of 56.28%, which can be attributed to its higher density, larger ceramic grains, and reduced low-frequency conductivity. The CaFeO3−δ ceramic sintered at 1200 °C/4 h shows a combination of high permittivity, enhanced conductivity, and strong ethanol sensitivity, making it a promising material for dielectric components, capacitive devices, and gas sensing applications.

Ceramics doi: 10.3390/ceramics9030032

Authors: Benyapa Korcharoenrat Tool Sriamporn Niyom Thamrongananskul Nantawan Krajangta Awiruth Klaisiri

The aim of this research was to assess the effects of different adhesive surface treatment protocols using universal adhesives on the shear bond strength (SBS) between a Vita Enamic and resin composite, as well as to analyze the associated failure modes. Eighty Vita Enamic ceramics were prepared, thermocycled, and randomly allocated into eight experimental groups following silane coupling agent pretreatment and adhesive system: Single Bond 2 (SB), silane + SB, Scotchbond Universal Plus (SBP), silane + SBP, Beautibond Xtreme (BEX), silane + BEX, Tetric N-Bond Universal (TUB), and silane + TUB. All specimens were etched with 9% hydrofluoric acid prior to adhesive application. Resin composites were bonded to the treated surfaces and subjected to SBS analysis using a universal testing device. Failure modes were performed under a stereomicroscope. Data were statistically determined using one-way ANOVA and Tukey’s post hoc test (α = 0.05). Statistically significant differences in SBS were indicated among the groups (p < 0.05). In the result, the SB (13.96 ± 2.34 MPa) and TUB (12.39 ± 2.91 MPa) groups exhibited the lowest SBS values and exclusively adhesive failure modes. Groups treated with silane and/or silane-containing universal adhesives (Sl + SB; 18.42 ± 3.11 MPa, SBP; 19.01 ± 2.62 MPa, BEX; 19.20 ± 2.96 MPa and Sl + TUB; 18.16 ± 2.82 MPa) demonstrated significantly higher SBS. The highest SBS values were achieved in the silane + SBP (24.53 ± 2.66 MPa) and silane + BEX (25.12 ± 2.74 MPa) groups, which were statistically comparable to each other and superior to all other groups. These groups also showed increased proportions of mixed and cohesive failures, indicating improved interfacial integrity. In conclusion, the SBS between Vita Enamic and the resin composite was significantly influenced by surface pretreatment and adhesive composition. Hydrofluoric acid etching combined with silane coupling agent pretreatment and silane coupling agent-containing universal adhesives provided the highest bond strength, supporting a multimodal strategy for the reliable repair of Vita Enamic restorations.

Ceramics doi: 10.3390/ceramics9030031

Authors: Eckart Uhlmann Xinyu Zhang Anton Hoyer

In this study, the material removal behavior of abrasive brushing tools on zirconia-toughened alumina cutting edges is experimentally investigated. Three different brushing tool specifications with bonded diamond grains are tested, varying in filament diameter, filament length, and grain size. Using an industrial robot setup, structured brushing experiments are performed on the cutting edges of indexable inserts under controlled variations of key process parameters, such as brushing velocity vb, axial feed rate vfa, infeed ae, and contact angle φ. The resulting edge rounding is quantified using three-dimensional optical scanning. Key metrics, such as edge radius rβ and form factor K, are evaluated to assess the suitability of abrasive brushing processes for the preparation of ceramic cutting edges. The results showed that the edge radius ranged from rβ = 20 to 80 µm, while the form factor varied from K = 1 to 3. The brushing velocity vb and axial feed rate vfa were identified as the primary parameters influencing the rounding radius rβ, whereas the infeed ae was the dominant parameter affecting the form factor K. While cutting edge preparation of metal and carbide tools is well studied, little research exists on abrasive brushing of zirconia-toughened alumina (ZTA) cutting inserts. Because ZTA behaves differently from metals, this study systematically investigates robot-assisted abrasive brushing of ZTA, analyzing how key process parameters affect edge radius, shape, and uniformity along the cutting edge.

Ceramics doi: 10.3390/ceramics9030030

Authors: Suela Hoxha Teuta Pustina-Krasniqi Fisnik Aliaj

The aim of this in vitro study was to evaluate and compare the color stability of different CAD/CAM ceramic materials after artificial aging induced by thermocycling. Two hundred disk-shaped specimens were fabricated from five CAD/CAM materials: high-translucent zirconia (HT), ultra-high-translucent zirconia (UHT), standard translucent zirconia (ST), a polymer-infiltrated hybrid ceramic (CERASMART 270), and a lithium disilicate glass-ceramic (GC Initial LiSi Block). Color measurements were performed at baseline and after 10,000 thermocycling cycles (5–55 °C) using a VITA Easyshade® spectrophotometer. Color coordinates (CIE L*, a*, b*) and overall color differences (ΔE) were calculated. Statistical analysis was applied to determine material-dependent differences. All materials exhibited statistically significant color changes after thermocycling (p < 0.001). The color change varied by material. Lithium disilicate showed the highest ΔE values, whereas UHT, HT zirconia and CERASMART 270 showed lower color changes, yielding results within clinically acceptable limits. Color stability after thermocycling is highly material-dependent. Zirconia-based and polymer-infiltrated ceramics showed superior optical aging resistance compared to lithium disilicate ceramics, indicating their clinical suitability for long-term esthetic CAD/CAM restorations.

Ceramics doi: 10.3390/ceramics9020029

Authors: Cesar Martins Fraga Edmilson Monteiro de Souza Alexander Machado Cardoso

Spent fluid catalytic cracking catalysts (E-cat) are a challenging waste from the petroleum refining industry, enriched with heavy metals such as nickel, vanadium, and iron. This study proposes a circular valorization strategy by incorporating E-cat into a chemically bonded iron phosphate ceramic matrix, known for its excellent waste stabilization properties. Composites were synthesized at room temperature using E-cat, hematite, and phosphoric acid, with E-cat contents from 0% to 35%. Characterization by XRF, XRD, SEM, compressive strength, and water absorption tests identified an optimal formulation containing 16% E-cat, achieving a maximum compressive strength of 16.6 MPa, 35% higher than the control. This improvement can be attributed to the dual function of E-cat, acting both as a micro-aggregate that promotes matrix densification and as a pozzolanic component that enhances mechanical reinforcement. These results demonstrate that iron phosphate ceramics represent a low-energy and sustainable strategy for the immobilization of spent catalysts and the production of durable construction composites.

Ceramics doi: 10.3390/ceramics9020027

Authors: Yuying Wang Chaoyang Liu Yanping Tan Songsong Zhang Ting Zhu Deyi Zheng Xingchao Tian

To synergistically integrate piezoelectric and varistor functionalities in a single material, PNN-PZT piezoelectric powder (abbreviated as P) and ZnO-based varistor powder (abbreviated as Z) were utilized to fabricate PZT-ZnO composite ceramics (denoted as PZm) via conventional solid-state sintering. The P/Z molar ratio was regulated to 1/0.9, 1/1.05, 1/1.2, 1/1.35, and 1/1.5 to systematically study its influence on the phase composition, microstructure, and electrical properties of the composites. XRD, SEM, EDS characterization, and electrical performance tests were carried out. Results indicate that all PZm samples exhibit the biphasic coexistence of perovskite (piezoelectric phase) and wurtzite (varistor phase) without impurity phases, consisting of large perovskite grains with distinct edges and small wurtzite grains with smooth surfaces. The PZ3 sample (P/Z = 1/1.2) achieves optimal comprehensive properties: d33 = 161 pC/N, kp = 0.25, Ɛr = 2527, tan δ = 3.83%, E1mA = 1396 V/mm, IL = 8.2 mA, α = 22.06. This work confirms the synergistic optimization of piezoelectric and varistor properties in PZT-ZnO composites, providing a reliable experimental basis for the formulation design and performance regulation of multifunctional ceramics.

Ceramics doi: 10.3390/ceramics9020028

Authors: Apichai Maneenacarith Tool Sriamporn Niyom Thamrongananskul Nantawan Krajangta Thanasak Rakmanee Awiruth Klaisiri

This in vitro study investigated whether piranha solution treatment, applied alone or following sandblasting, enhances the shear bond strength of resin cement to zirconia. Fifty zirconia specimens were assigned to five groups: no treatment, sandblasting (SB), piranha solution (Pi), sandblasting followed by piranha solution treatment (SB + Pi), and double piranha treatment (Pi + Pi). Shear bond strength was measured after 24 h water storage, and failure modes were recorded. The SB + Pi group produced significantly higher bond strength than all other groups. Single treatments (SB, Pi, and Pi + Pi) yielded statistically comparable values, all exceeding the untreated control. Notably, double piranha application offered no benefit over a single application. These findings are preliminary and limited to short-term in vitro conditions; the piranha protocol is not feasible for direct clinical use due to safety constraints, and no aging or surface characterization data were obtained.

Ceramics doi: 10.3390/ceramics9020026

Authors: Diana Vitiello Ilona Kieliba Sawao Honda Benoit Nait-Ali Nicolas Tessier-Doyen Hans Ulrich Marschall David S. Smith

Alumina-spinel refractory bricks, composed of 82 wt.% alumina and 18 wt.% MgAl2O4 spinel phases, are used in steel ladles due to their ability to resist chemical attack and thermal shock. Thermal shock resistance is determined, in part, by the thermal conductivity of the material. Thermal conductivity measurements for alumina-spinel refractory, three model alumina ceramics, and single crystal sapphire were made with the laser-flash technique from 20 °C to 1000 °C. At room temperature, these gave 6.5 W m−1 K−1 for the refractory, 5.8 to 22 W m−1 K−1 for the alumina ceramics, and 36 W m−1 K−1 for sapphire, despite all materials containing >81 vol.% of alumina. The differences are explained by the roles of porosity, grain boundary thermal resistance, and the spinel phase (refractory). In order to estimate the thermal conductivity of alumina grains in each material, these microstructural effects are modelled with Landauer’s relation for porosity and thermal resistors in series for grains combined with grain boundaries. For two alumina ceramics, the grains yielded similar behaviour to the single crystal. By taking the spinel phase into account with a two-phase mixture relation, the alumina grains in the refractory were estimated with a value of 31 ± 2 W m−1 K−1, close to sapphire.

Ceramics doi: 10.3390/ceramics9020025

Authors: Shenglin Li Baozhen Chen Yuanpeng Sun Yan Wang Keyao Xie Xuepeng Chen

In response to the high stiffness and hardness levels of alumina ceramic materials, the traditional SHPB (split Hopkinson pressure bar) experimental setup has been modified. This study analyzes the propagation patterns of stress waves in the SHPB system after adding cushion blocks. Experiments demonstrated that the modified SHPB apparatus can effectively perform dynamic mechanical property tests on alumina ceramics. The JH-2 constitutive damage model parameters for alumina ceramics were determined based on theoretical analysis and static/dynamic experimental data. An LS-DYNA numerical model for the impact compression simulation of alumina ceramics was established to investigate the effects of stress waves with three wavelengths (300 mm, 400 mm, and 600 mm) at the same impact velocity, along with the dynamic fragmentation process. The results indicate that alumina ceramics exhibit strain rate hardening effects in compressive strength, failure strain, and elastic modulus under high strain rates; compressive strength and failure strain show positive correlations with stress wave wavelength under high strain rates; and microcracks initially nucleate preferentially along grain boundaries on the end surfaces, forming annular damage zones symmetrically about the central axis. This study presents a modified SHPB setup that improves test capability for high-hardness ceramics, rather than overturning classical methodologies. The absence of a direct comparison with unmodified setups stems from the known limitations of conventional systems in handling small-diameter alumina specimens without bar damage—a challenge addressed proactively in this work through impedance-matched cushion blocks and refined data processing.

Ceramics doi: 10.3390/ceramics9020024

Authors: Abigail Parra Parra Rene Guardian Tapia Ximena Cecilia Ramírez López Marina Vlasova Pedro Antonio Márquez Aguilar

This work analyzes phase transformations in quaternary mixtures (clay–glass–hematite–waste activated sludge (WAS)), processed at 800–1000 °C under conditions of oxygen deficiency. The results of the study showed that, depending on the temperature treatment of mixtures of different compositions, the processes of carbon formation from WAS, carbon participation in reductive processes, and phase transformations in silicate subsystems occur simultaneously. After Ttr = 800 °C the main phases are fayalite and quartz, additional phases are wollastonite and feldspars. After Ttr = 900 °C the main phases are fayalite, quartz, wollastonite, and the additional phases are feldspars. After Ttr = 1000 °C the main phases are wollastonite, iron, quartz, additional phases are hematite, fayalite.

Ceramics doi: 10.3390/ceramics9020023

Authors: Yang Wang Naoyuki Hashimoto Hiroshi Oka Shigehito Isobe

High-purity Zr3AlC2 samples (>92 wt%) were synthesized and irradiated at room temperature using 100 keV He+ ions at fluences of 2 × 1016 and 1 × 1017 ions/cm2. As a Zr-based MAX phase, Zr3AlC2 is a promising candidate for accident-tolerant fuel cladding due to its compatibility with Zr alloys and the low neutron absorption cross-section of Zr. Our results show that irradiation induces a decrease in the a-lattice parameter and an increase in the c-lattice parameter, along with the formation of anti-site defects and decomposition into ZrC. Cracks preferentially appear along (1000) planes. These findings suggest that Zr3AlC2 has limited structural stability under low-temperature helium irradiation.

Ceramics doi: 10.3390/ceramics9020022

Authors: Xuan Lv Zhen Wang Maolin Zhang Min Wang Guoping Pan

Longquan celadon represents the pinnacle of Chinese celadon, and there are many kilns in southern China that imitate Longquan celadon. During the Ming Dynasty, Jianyang Bowl Kiln was the representative kiln in Fujian Province for imitating Longquan celadon, while Jingdezhen Kiln was the representative kiln in Jiangxi Province for imitating Longquan celadon. The quality of both is close to that of Longquan celadon, making it difficult to distinguish by ordinary visual observation. This study focuses on Jianyang Bowl Kiln and Jingdezhen Kiln imitating Longquan celadon, comprehensively employing methods such as EDXRF, LA-ICP-MS, and chromaticity analysis to systematically investigate the similarities and differences in the composition of their body and glaze. The results indicate that distinct differences exist in the composition of trace and rare earth elements between the imitations of Longquan celadon produced by Jianyang Bowl Kiln and Jingdezhen Kiln, and authentic celadons from Longquan Kiln, which can serve as important criteria for distinguishing kilns. This provides systematic scientific data support for identifying the technological origins and production locations of Ming Dynasty imitations of Longquan celadon.

Ceramics doi: 10.3390/ceramics9020021

Authors: Chung-Yung Lin Yu-Chang Liu Bang-Lun Jhou

The selective removal of radioactive cesium-137 and strontium-90 from high-salinity radioactive wastewater remains a critical challenge, as competing ions reduce adsorption efficiency and selectivity. In this study, high-performance granulated adsorbents were developed based on alkali-activated geopolymer matrices to enhance sorption performance. The adsorbents were synthesized by inorganic polymerization, and mechanically robust granules with controlled porosity and surface chemistry were obtained. Batch sorption experiments conducted in simulated seawater demonstrated greater than 99% removal efficiencies for cesium and strontium. Isotherm modeling confirmed high maximum sorption capacities (up to 0.41 meq/g for Cs+ and 5.07 meq/g for Sr2+). Continuous fixed-bed column tests demonstrated sustained removal efficiencies for the optimized adsorbents. Structural analyses, including scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, and X-ray diffraction, confirmed uniform elemental distribution and crystalline phases consistent with selective sorption mechanisms. Assessment of mechanical strength revealed sufficient compressive strengths to ensure operational durability under hydraulic stress. These findings demonstrate that the synthesized geopolymer-based granules are a potentially effective and versatile solution for the comprehensive treatment of radioactive wastewater.

Ceramics doi: 10.3390/ceramics9020020

Authors: Yuying Song Wenfeng Yue Fu Huang Yuqun Deng Yongjiang Zhang Junyu Ming Fayaz Hussain Adil Alshoaibi Gulmurza Abdurakhmanov Junjun Wang Dawei Wang

Dielectric capacitors, characterized by ultra-fast charge/discharge speeds and high power densities, are widely used in modern electronic power systems. However, their low energy density and poor thermal stability limit applications. In this study, SrBi3.25La0.75Ti4O15 (SBLT) ferroelectric thin films were prepared by the sol–gel method. We systematically investigated the effect of annealing temperature on microstructural evolution, electrical properties, and energy storage performance. The SBLT film annealed at 700 °C exhibited optimal performance, achieving a balanced enhancement in polarization and breakdown strength, with an energy storage density of 48.66 J cm−3 and an efficiency of 78%. The material also demonstrated excellent thermal stability (30–175 °C) and frequency stability (0.1–100 kHz). These findings not only validate the potential of SBLT as a next-generation energy storage dielectric but also provide a practical solution for applications in semiconductor technology.

Ceramics doi: 10.3390/ceramics9020019

Authors: Oscar Graos-Alva Aldo Castillo-Chung Juan Carlos Rodríguez-Soto Carlos Vásquez-Boyer Alexander Vega-Anticona

Valorizing construction and demolition waste (CDW) via alkaline activation enables low-carbon binders. This study assesses binary geopolymers formulated with recycled brick powder (PLR) and recycled concrete powder (PCR) in seven precursor ratios (0–100% PCR), activated with a ternary NaOH/Na2SiO3/KOH solution (silicate modulus Ms ≈ 3.2) at L/B = 0.15, and cured for 7, 14, and 28 days. Compressive strength (fc), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) were used to link microstructure–phases–properties. A local maximum in fc at ~30% PCR (16.2 MPa at 28 d) was observed versus 0% PCR (14.2 MPa) and ≥50% PCR (13.8 → 10.1 MPa at 28 d). XRD indicated a reduction in inherited crystalline phases and an increased amorphous fraction at ~30% PCR; FTIR (normalized peak position and FWHM of the T–O–Si band, not absolute intensity) suggested higher network extension; SEM-EDS (local/semiquantitative) showed a moderate rise in Ca that supports C-A-S-H domains bridging the N-A-S-H network. At a high PCR, excess Ca simplified mineralogy (quartz/portlandite dominance), promoted competitive routes (C-S-H/carbonation), reintroduced microdefects, and reduced fc. A theoretical oxide balance per mix identified a compositional window where Ca/(Si + Al) ≈ 0.35–0.45 coincides with the mechanical optimum and with XRD/FTIR tracers. Overall, a ~30% PCR window maximizes co-reticulation of N-A-S-H/C-A-S-H and densification without compromising aluminosilicate continuity, providing transferrable design and process-control criteria for CDW-based geopolymer binders.

Ceramics doi: 10.3390/ceramics9020018

Authors: Jia Li Huitao Guo Yuxin Chen Guifen Fan Fangfang Zeng

As the operational demands on piezoelectric devices grow increasingly stringent, there is an urgent need for materials capable of delivering stable performance at elevated temperatures. BiFeO3 (BF), a lead-free piezoelectric oxide with high-temperature resilience, is characterized by its notably high Curie temperature (Tc ∼ 835 °C), rendering it a promising candidate for high-temperature applications. However, its piezoelectric coefficients remain inadequate to satisfy practical requirements. The 0.7BiFeO3-0.3Ba(1-x) SrxTiO3 system (abbreviated as BF-BSxT) was designed to elucidate the roles of chemical disorder and local structural heterogeneities in the enhancement of functional properties through fine-tuning of the Sr content. The phase structure of the samples was carefully examined by X-ray diffraction. Rietveld refinement of the XRD data revealed that all BF-BSxT ceramics consist of coexisting R and PC phases. Optimized compositional disorder and local heterogeneities led to a moderate enhancement in the piezoelectric coefficient d33 value of 160 pC/N, a high Tc of 495 °C, and a remanent polarization Pr ≈ 22.1 μC/cm2 -were achieved in the BF-BSxT system at x = 0.06. These results indicate that BF-BSxT ceramics hold good potential for use in high-temperature piezoelectric devices.

Ceramics doi: 10.3390/ceramics9020017

Authors: Caterina Sgarlata Luciana Cupertino Lorenzo Serafini Cristina Siligardi

The ceramics industry has long embraced the principles of the circular economy, with a strong focus on the reuse and recovery of raw materials essential to the production cycle. This approach reduces costs by reintroducing secondary raw materials—such as production scraps and recycled materials—into the manufacturing process after appropriate recovery treatments. This study aims to contribute to the transition of the ceramic industry toward a circular economy by incorporating industrial by-products into monoporosa ceramic bodies, thereby transforming waste materials into valuable resources. Monoporosa is a porous, single-fired ceramic wall tile characterized by a high carbonate content and low bulk density. However, the role of secondary raw materials in monoporosa formulations, as well as their influence on processing behavior (e.g., during sintering) and on key technological properties, is not yet fully understood. This work investigates a standard monoporosa formulation based on conventional raw materials (sand, calcite, feldspars, and clays) and compares it with new formulations in which industrial waste materials from local and national sources—originating from other industrial processes—are used as partial or total substitutes for some of the traditional raw materials, particularly sand and calcite. The industrial by-products examined include biomass bottom ash, foundry sand, and marble cutting and processing sludge. All materials were characterized using chemical–mineralogical, thermal, and morphological analyses and were incorporated into the ceramic bodies at different substitution levels (10%, 50%, and 100%) to replace natural raw materials. Their behavior within the mixtures was evaluated to determine ceramic suitability and acceptable replacement ratios. Furthermore, the effects of these additions on water absorption, thermal expansion coefficient, and microstructural characteristics were assessed. Based on the positive results obtained, this study demonstrates the feasibility of using, in particular, two secondary raw materials—foundry sand and marble sludge—in monoporosa body formulations, allowing for the complete replacement of the original raw materials and thereby contributing to the development of more sustainable ceramic compositions.

Ceramics doi: 10.3390/ceramics9020016

Authors: Edwin Francis Cárdenas Correa Edgar Absalón Torres Barahona Juan Bautista Carda Castelló

In additive manufacturing technologies, the use of pastes and inks based on materials such as clay to create three-dimensional objects layer by layer has opened new possibilities in fields such as engineering and biomedicine. This review article aims to provide a comprehensive understanding of 3D printing of ceramic pastes through Direct Ink Writing (DIW), also referred to as Robocasting. DIW offers specific advantages for ceramic 3D printing, including the ability to extrude highly loaded pastes with customized rheological properties to accommodate a broad spectrum of ceramic compositions, varying from conventional clays to advanced ceramics. It is characterized by filament deposition control, which facilitates the fabrication of complex, porous, or customized architectures while simultaneously minimizing material waste. Through a bibliometric analysis of the literature published between 2020 and 2024, the most relevant studies regarding printing system architectures, ceramic paste formulations, and adjustment of parameters to obtain high-quality parts were identified. This work presents relevant and accurate explanations of the DIW technology, supporting researchers and industry professionals seeking to initiate or improve ceramic 3D printing processes for a wide range of applications.

Ceramics doi: 10.3390/ceramics9020015

Authors: Jie Feng Xishun Zheng Deyi Zheng

Bismuth layer-structured ferroelectrics (BLSFs) are core candidates for high-temperature piezoelectric applications owing to their excellent thermal stability and fatigue resistance, yet traditional Bi4Ti3O12 (BiT)-based ceramics suffer from limited piezoelectric performance. To address this, MBi4Ti4O15-Bi4Ti3O12 (M=Ba, Sr, Ca) symbiotic structure bismuth-layered piezoelectric ceramics were fabricated via the conventional solid-state reaction method. Their crystal structure, microstructure, and electrical properties were systematically characterized using a X-ray diffractometer, scanning electron microscope, high-temperature dielectric spectrometer, and quasi-static d33 meter to explore the effects of different A-site divalent elements. Results show that all samples form a pure-phase symbiotic structure with the P21am space group, without secondary phases. The lattice constant decreases with increasing A-site ionic radius, while symbiosis-induced lattice mismatch and long-range disorder refine grains, reduce aspect ratio, lower conductivity, enhance spontaneous polarization, and improve piezoelectric properties. The ceramics exhibit d33 of 10 to 15 pC/N and TC of 502 to 685 °C, with SrBi4Ti4O15-Bi4Ti3O12 showing optimal comprehensive performance (d33 ≈ 15 pC/N, TC = 593 °C, tanδ = 0.6% at 1 kHz/475–575 °C, and a low AC conductivity of 5.3 × 10−5~4.8 × 10−4 S/m). This study improves bismuth-layered ceramics’ performance via A-site regulation and symbiotic structure design, offering theoretical and technical support for high-performance lead-free high-temperature piezoelectric ceramics.

Ceramics doi: 10.3390/ceramics9020014

Authors: Seung Joon Yoo Ji Su Kim Jung Hoon Choi Jin Ho Kim Kyu Sung Han Ung Soo Kim

Alumina ceramics used in semiconductor plasma environments require high densification, microstructural homogeneity, and stable performance under increasingly aggressive processing conditions. However, systematic studies linking slurry processing parameters to the plasma resistance of alumina ceramics remain limited. In this study, the effects of slurry preparation parameters—specifically milling and aging—and sintering atmosphere on the densification, mechanical strength, and plasma etching resistance of slip-cast alumina ceramics were systematically investigated. Optimal dispersion stability was achieved under 12 h milling and 12–24 h aging conditions, resulting in homogenized green body packing and a high relative sintered density exceeding 99%. Mechanical strength and plasma resistance were strongly influenced by slurry aging and sintering atmosphere. Specimens aged for 48 h and sintered under a low oxygen partial pressure (N2 at 1.0 L/min) exhibited the highest flexural strength and significantly improved resistance to SF6/Ar plasma etching, with reduced etch depth and suppressed surface roughening. These results demonstrate that coordinated slurry processing and sintering atmosphere control is an effective strategy for designing high-reliability, plasma-resistant alumina ceramics for high-demand semiconductor manufacturing environments.

Ceramics doi: 10.3390/ceramics9020013

Authors: Saúl Alberto Guerrero Rivero Leticia da Silva Gondim Joana B. Torres André Teixeira Nireide Pereira Tavares Jaylson Monteiro Javier Iñañez

Archaeological research on Santiago Island (Cape Verde) offers a strategic framework for investigating ceramic material culture shaped by Iberian and African interactions during the early modern period. This study presents first-stage results from a non-destructive archaeometric analysis of pottery fragments recovered from early colonial sites and curated at the Museu de Arqueologia in Praia. Using portable X-ray fluorescence spectroscopy (pXRF), low-fired, handmade vessels associated with African technological traditions were analysed to determine their elemental composition and potential provenance. The work also focused on sugar moulds, containers used in the refining of this product, one of the most important in Atlantic colonisation. The resulting geochemical data is compared with established reference groups from the Iberian Peninsula, Atlantic Africa, and Macaronesia. Elemental variability indicates the use of diverse clay sources and production techniques, reflecting hybrid technological practices shaped by cultural interaction and provisioning constraints. These results contribute to ongoing research within the CERIBAM (Iberian Atlantic Expansion in North Africa and Macaronesia) and Palarq-funded projects, which aim to reconstruct early colonial ceramic networks and sociotechnical dynamics. By integrating archaeometric data with archaeological and historical perspectives, this study aims to demonstrate the utility of non-invasive analytical protocols for understanding ceramic technology, intercultural exchange, and Atlantic material connectivity in early Creole formations while preserving the integrity of the collections.

Ceramics doi: 10.3390/ceramics9020011

Authors: Arianna Bertero Bartolomeo Coppola Laura Montanaro Matteo Bergoglio Paola Palmero Jean-Marc Tulliani

Digital Light Processing (DLP), which operates through a layer-by-layer deposition, has proven to be a promising technique for obtaining complex and customized architectures. However, there are still numerous unresolved challenges in ceramics additive manufacturing, among which is delamination due to suboptimal adhesion between the layers, which threatens the structural integrity and properties of samples. According to recent findings, excess surface hydroxyl groups were identified as being responsible for this defect; a suitable calcination pre-treatment of the ceramic powder could be effective in significantly mitigating delamination flaws in mullite DLP printed bodies. Therefore, in addition to optimizing the printable slurry formulation and printing parameters (mainly in terms of curing energy and layer resolution), this work aimed at investigating the influence of the calcination of a commercial mullite powder (added with magnesium nitrate hexahydrate, as a precursor of the sintering aid MgO) as a simple and effective treatment to additively shape ceramic bodies with limited flaws and enhanced density. The surface characteristics evolution of the mullite powder was investigated, specifically comparing samples after magnesium nitrate hexahydrate addition and ball-milling in water (labeled as BM), and after an additional calcination (BMC). In particular, the effect of the superficial -OH groups detected by FTIR analysis in the BM powder, but not in the BMC sample, was studied and correlated to the properties of the respective ceramic slurry in terms of rheological behavior and curing depth. The hydrophilicity of BM powders, due to superficial hydroxyls groups, affects ceramic powder dispersion and wettability by the resin, causing a weak interface. At the same time, it promotes photopolymerization of the light-sensitive resin, thus inducing the as-printed matrix embrittlement. Anyhow, its photopolymerization degree, equal to 67% and 55% for BM and BMC, respectively, was enough to guarantee the printability of both slurries. However, the use of BMC significantly reduced flaw occurrence in the as-printed bodies and the final density of the samples sintered at 1450 °C (without an isothermal step) was increased (approx. 60% and 50% of the theoretical value for BMC and BM, respectively). Thus, the target porosity of the ceramic bodies was guaranteed, and their structural integrity achieved without any increase in sintering temperature but with a simple powder treatment.

Ceramics doi: 10.3390/ceramics9020012

Authors: Hadjer Youcef Mohamed Toufik Soltani Dominique de Ligny

Boro-antimonite glasses doped with Eu3+ and having the general composition (90-x) Sb2O3–xB2O3–10Li2O-0.5Eu2O3 (x = 0 to 60 in 10 mol. % increment) were prepared using the melt quenching method. The influence of B2O3/Sb2O3 substitution on the spectroscopy and photoluminescence of Eu3+ ions was analyzed by studying the measured and calculated properties of these glasses. The relative value of a given property was shown to increase or decrease by up to 26% with the addition of up to 60 mol. % B2O3, while the number of Eu3+ ions per unit volume increased by approximately 32%. Strong emissions were obtained in association with the transitions of Eu3+ (5D0→7Fj, j = 1–4). A weak, broad emission centered at 450 nm was also detected. This emission is clearly linked to the glass composition. It originates from a potential presence of Eu2+ ions. This enhances 5D0 level emission via charge transfer. The radiative and experimental lifetimes of the 5D0 level increase linearly with B2O3 content. This results in high quantum efficiency (η) ranging from 74 to nearly 84%. Tunable chromaticity, as defined by the CIE 1931 standard, was achieved, resulting in a warm orange-red color with high brightness. These new glasses have a variety of potential laser-related applications.

Ceramics doi: 10.3390/ceramics9010010

Authors: Beata Śmielak Leszek Klimek Marco Ferrari Kamil Krześniak

How does zirconia processing affect the degree of tetragonal to monoclinic phase transformation (t ⟶ m) and the development and wettability of the surface? One hundred and twenty-four samples made of sintered zirconium were divided into four groups based on the following treatments: grinding, polishing, sandblasting with Al2O3, or sandblasting with SiC. After surface treatment, the samples were subjected to the following tests: X-ray diffraction, microscopic examination, surface roughness measurements, and surface wettability. The highest values are achieved after the grinding process (Ra = 0.63; Rz = 9.29; Rq = 1.28), and the lowest values are found after polishing (Ra = 0.11; Rz = 0.71; Rq = 0.36). All samples, apart from those sandblasted with Al2O3 (Θ = 121.59°), showed wettability with the polar liquid. The best wettability was noted for sandblasted SiC samples (Θ = 41.22°) and the lowest was noted for polished samples (Θ = 80.61°). All samples showed wettability with an apolar liquid (Θ < 90°). A significant transformation (t ⟶ m) was noted in all tested samples: about 14% for ground, 17% for polished, 13.8% for Al2O3 sandblasting, and 13.1% for SiC sandblasting samples. The type of processing method has a significant impact on the selected parameters of roughness, surface wettability, and phase transformations.

Ceramics doi: 10.3390/ceramics9010009

Authors: Lijuan He Yuhang Huang Jianhua Zhou Yi Wang Jingwei Yang Xuan Liu Shuping Wang Zhigang Zhang

This study systematically examines the fluidity, setting time, mechanical properties, and microstructural evolution of metakaolin-based geopolymer grouting materials with a relatively high water-to-solid (W/S) ratio window. A four-factor, three-level orthogonal experimental design was employed to identify the dominant factors and main effect trends of W/S ratio, alkali dosage, water glass modulus (Ms, molar ratio of SiO2 to Na2O in alkali solution), and steel slag content on the material’s performance. The results indicated that the W/S ratio predominantly governed fluidity, while the alkali content was the primary controlling factor for setting time and early-age strength. An intermediate range of water glass modulus with a value of 1.6 provided balanced performance. The incorporation of steel slag with a range of 10–20% showed an age-dependent contribution: it not only tended to improve the rheology of the paste but also the later-age strength. XRD, FTIR, and SEM/EDS results suggested that the hardened binders were dominated by amorphous products, where alumimosilicate gel (N-A-S-H) and Ca-containing gel (C-S-H/C-A-S-H) may coexist depending on calcium availability and activator chemistry. The proposed parameter ranges are valid within the studied design space and provide guidance for the mix design of high-W/S geopolymer grout.

Ceramics doi: 10.3390/ceramics9010008

Authors: Kyung Hoon Sun Cheol Hee Choi Chul Ho Jang

Canal wall down mastoidectomy (CWD) effectively eradicates cholesteatoma and chronic otitis media but frequently results in a problematic open mastoid cavity. Mastoid obliteration aims to reduce cavity-related morbidity. Bioceramic materials, including hydroxyapatite (HA), tricalcium phosphate (TCP), and bioactive glass (BAG), have been increasingly adopted because of their osteoconductive, biocompatible, and antimicrobial properties. This systematic review evaluates the clinical outcomes and complications of bioceramic mastoid obliteration following CWD. A systematic literature search of PubMed, Scopus, and Web of Science was conducted for studies published between 2005 and 2025, following PRISMA guidelines. Clinical studies reporting outcomes of bioceramic mastoid obliteration after CWD were included. Thirteen clinical studies were included. HA-, TCP-, and BAG-based materials demonstrated high obliteration success rates (>90% in most series). BAG S53P4 was consistently associated with low infection rates and favorable epithelialization, whereas earlier HA cement formulations were occasionally associated with revision-requiring complications. Bioceramic scaffolds represent safe and effective materials for mastoid obliteration after CWD. BAG offers additional antibacterial advantages, while HA provides predictable volume stability. Further prospective and comparative studies are required to establish material superiority and long-term outcomes.

Ceramics doi: 10.3390/ceramics9010007

Authors: Habib Rostaghi Chalaki Ebenezer Seesi Mohammad El Loubani Dongkyu Lee

Sluggish oxygen reduction reaction (ORR) remains a critical barrier to advancing intermediate-temperature electrochemical energy devices. Here, we demonstrate that strain engineering in two platforms, epitaxial thin films and freestanding membranes, systematically tunes ORR kinetics in Ruddlesden-Popper LaSrCoO4. In epitaxial films, film thickness is varied to control in-plane tensile strain, whereas in freestanding membranes strain relaxation during the release step using water-soluble sacrificial layers produces flat or wrinkled architectures. Electrochemical impedance spectroscopy analysis reveals more than an order of magnitude increase in the oxygen surface exchange coefficient for tensile-strained films relative to relaxed films, together with a larger oxygen vacancy concentration. Wrinkled freestanding membranes provide a further increase in oxygen surface exchange kinetics and a lower activation energy, which are attributed to increased active surface area and local strain variation. These results identify epitaxial tensile strain and controlled wrinkling as practical design parameters for optimizing ORR activity in Ruddlesden-Popper oxides.

Ceramics doi: 10.3390/ceramics9010006

Authors: Josef Škvarka Iva Janáková František Pticen Radmila Kučerová

This study focuses on preparing mullite grogs derived from selected waste materials and kaolin treated with advanced technologies to achieve high thermal resistance and low thermal expansion. The investigated waste materials include dust removal RON, slurry DE, feldspar dust removal from Halamky, and waste generated during the feldspar grinding at the Halamky I deposit. These materials (Red kaolin from Vidnava, Slurry DE, Dust-off RON, Feldspar dust-off Halamky) were processed into grogs and subsequently applied for the production of high-mullite ceramics. The influence of cristobalite admixture was also assessed. The chemical composition was determined by X-ray fluorescence (XRF), while the phase composition was analysed by X-ray diffraction (XRD). Amorphous mullite grogs with mullite contents greater than 40% were successfully prepared. Despite the relatively high iron content, the resulting products exhibited the desired white colour after firing and demonstrated properties that make them promising candidates for advanced refractory applications. The study highlights the potential to valorise industrial waste materials for high-value ceramic applications.

Ceramics doi: 10.3390/ceramics9010005

Authors: Xiaoran Li Lu Ren Changxin Li Lili Zhang Jincheng Ji Mao Peng Pengyu Xu

The development of lithium-ion batteries necessitates cathode materials that possess excellent mechanical and thermal properties in addition to electrochemical performance. As a prominent functional ceramic, the properties of spinel LiMn2O4 are governed by its atomic-level structure. This study systematically investigates the impact of Ni doping concentration on the mechanical and thermal properties of spinel LiNixMn2−xO4 via first-principles calculations combined with the bond valence model. The results suggest that when x = 0.25, the LiNixMn2−xO4 shows excellent mechanical properties, including a high bulk modulus and hardness, due to the favorable ratio of bond valence to bonds length in octahedra. Furthermore, this optimized composition shows a lower thermal expansion coefficient. Additionally, Ni doping concentration has a very minimal influence on the maximum tolerable temperature of the cathode material during rapid heating. Therefore, from the perspective of mechanical and thermal properties, this composition could be beneficial for improving the cycling life of the battery, since comparatively inferior mechanical properties and a higher thermal expansion coefficient make it prone to microcrack formation during charge–discharge cycles.

Ceramics doi: 10.3390/ceramics9010004

Authors: Almiro Mendes Costa Neto Caterine Yesenia Carrasco Montesdeoca Bruno Pereira da Silva Neto Amanda Miranda Franco Antonio Linkoln Alves Borges Leal Humberto Medeiros Barreto Anderson Oliveira Lobo Fernanda Roberta Marciano

This manuscript describes the development of a nano-sized synthetic smectic clay hydrogel (LAP) that enables controlled oxygen delivery, making it a promising candidate for treating skin wound infections and promoting healing. LAP is an ingredient in various dermatological products, including powders, creams and emulsions. We investigated the antibacterial effect of the LAP hydrogel by incorporating calcium peroxide (CPO), an oxygen-releasing agent, and measuring the size of the inhibitory halo. We found that CPO hydrogels in LAP showed a significant increase in oxygen release during the first five hours, especially at low CPO concentrations. For example, the hydrogel with 5% CPO showed a controlled release profile with a final percentage oxygen release of 2.47 ± 0.01% after 5 h. In contrast, the hydrogels with 10% and 20% CPO achieved lower final oxygen release values, 0.67 ± 0.01% and 0.75 ± 0.01%, respectively, suggesting that the encapsulation efficiency of LAP is higher at higher concentrations. LAP also proved to be an effective oxygen barrier and showed inherent antimicrobial activity. The research confirmed the antibacterial properties of the hydrogel, with inhibition sites observed against both E. coli and S. aureus. These results emphasize the potential of this hydrogel to serve as an effective tool for wound treatment by providing sustained oxygenation and fighting microbial infections.

Ceramics doi: 10.3390/ceramics9010003

Authors: Ahmed H. Albaqawi Mohamed F. Metwally Sami A. Almohefer Walid A. Abdelhady Moazzy I. Almansour Khaled M. Haggag Hend M. El Sayed Ferdous Bukhary Ahmed A. Madfa

This in vitro investigation evaluated the marginal fit of three pressable glass-ceramic onlay materials: a conventional monolithic lithium disilicate (IPS e.max Press, EM, ivoclar vivadent AG, Schaan, Liechtenstein) and two zirconia-reinforced glass-ceramics (Vita Ambria, VA, VITA Zahnfabrik, Bad Säckingen, Germany; Celtra Press, CP, Sirona Dentsply, Milford, CT, USA). A typodont maxillary first premolar was prepared for an intensive onlay design by a single operator using a milling surveyor. The master die was duplicated with silicone impressions to create 72 identical epoxy resin dies. Seventy-two onlays (n = 24 per material) were fabricated and adhesively cemented to their respective dies. Vertical marginal gaps were recorded under a stereo-electron microscope before and after thermomechanical loading (TML) in a chewing simulator. Data were analyzed with one-way ANOVA and Tukey’s post hoc tests for intergroup comparisons and paired t-tests for pre- versus post-TML values. All groups showed a significant increase in marginal gap following TML. VA exhibited mean gaps of 46.41 µm before and 57.28 µm after loading (p = 0.001). EM demonstrated 41.16 µm before and 46.63 µm after TML (p = 0.002). CP showed 45.70 µm before and 55.99 µm after TML (p = 0.003). Among the three materials, EM maintained the most accurate marginal adaptation both before and after simulated chewing. Despite the increases, all post-loading values remained within the clinically acceptable threshold for marginal discrepancy. These findings indicated that thermomechanical fatigue adversely affected the marginal integrity of pressable glass-ceramic onlays, including zirconia-reinforced formulations. Nevertheless, zirconia-reinforced ceramics (VA and CP) achieved marginal gaps comparable to conventional lithium disilicate and remained within acceptable clinical limits. IPS e.max Press provided the best overall fit, suggesting it may offer superior long-term marginal stability for onlay restorations.

Ceramics doi: 10.3390/ceramics9010002

Authors: Ekaterina Kuznetsova Anton Smirnov Nestor Washington Solís Pinargote Roman Khmyrov Daniil Strunevich Natella Krikheli Oleg O. Yanushevich Pavel Peretyagin Andrey V. Gusarov

Highly filled (78 wt.%) alumina filaments with various (0.05, 0.10, 0.25 vol.%) graphene oxide concentration for Fused Filament Fabrication (FFF) were obtained. In order to evaluate the effect of graphene oxide on density, microstructure, and hardness, the fabricated materials were sintered in an argon atmosphere at 1500 °C and 1550 °C. A sample that was sintered under the same conditions in air was used as a control. Raman spectroscopy confirmed the reduction in graphene oxide and the absence of carbon in samples sintered in argon and air, respectively. In addition, in the samples with graphene oxide, the alumina grain size was lower than in air-sintered samples. The composite with the lowest amount (0.05 vol.%) of graphene oxide showed the highest value (1670.73 ± 136.9 HV) hardness.

Ceramics doi: 10.3390/ceramics9010001

Authors: Astrid Holzheid Stefanie Hildebrandt Eleonora Kulik Bernhard Durschang Catherine A. Macris David W. Wallington Klaus-Dieter Schicke

Three processes for the production of ceramics close to stoichiometric MgAl2O4 are benchmarked against each other. The traditional ceramic route is based on mostly crystalline starting powder, which is converted into ceramic via shaping and heat treatment (IKTS). The other two processes are based on glasses. Partial or complete crystallization without pressure (ISC) or complete crystallization with pressure (CAU) leads to (glass) ceramics. Spinel powder is mixed with various dopants (BaO, TiO2, CaO and SrO), with the aim to reduce the grain size (IKTS). The doping results in a second, partly interfering phase, and the transmission decreases strongly due to absorption with increasing content of the added oxide. For the glass route without pressure (ISC), it is shown that a network-forming oxide (B2O3, TiO2) is needed to produce the glasses. Compared to the starting glasses, the resultant glass ceramics suffer loss of transparency due to crystallization. Using the levitation furnace, it is possible to produce amorphous glass beads from MgAl2O4 enriched with 25 wt% SiO2 without a container. The nanocrystalline ceramics synthesized from these glasses and the ISC glasses via the high-pressure route (CAU) are moderately transparent to translucent.

Ceramics doi: 10.3390/ceramics8040155

Authors: Kacper A. Prokop Sandrine Cottrino Vincent Garnier Gilbert Fantozzi Miłosz Siczek Krzysztof Rola Elżbieta Tomaszewicz Yannick Guyot Georges Boulon Małgorzata Guzik

This work highlights the feasible fabrication of translucent ceramics from un-doped and Nd3+-doped BaLaLiWO6 (BLLW) and BaLaNaWO6 (BLNW) cubic tungstates using the Spark Plasma Sintering (SPS) method. Ceramics were sintered using pure-phase, homogeneous powders with submicron particle sizes, obtained via the solid-state reaction method. The present study investigated the microstructural, structural, and spectroscopic properties of both un-doped and Nd3+-doped sintered specimens. All the ceramic materials exhibited certain drawbacks that significantly contributed to their low transparency in both sample types. However, initial spectroscopic tests on sintered translucent ceramics doped with Nd3+ ions revealed promising properties, comparable to those of the powdered samples. Therefore, we believe that producing higher-quality ceramics would improve their spectroscopic properties. For that, further optimization of the manufacturing conditions is necessary.