Ceramics

High-entropy materials have emerged as promising candidates for high-temperature structural, magnetic, and electrochemical applications due to their unique combination of compositional complexity, thermal stability, and tailored functionality. In this study, self-propagating high-temperature synthesis (SHS) was employed to fabricate high-entropy composite in a Ti–Cr–Mn–Co–Ni–Al–C multicomponent system with a focus on elucidating the effect of titanium content on the combustion parameters, as well as on the phase and structure formation patterns of the resulting materials. In situ profiling enables evaluating the maximum combustion temperature of 1560 °C, combustion wave propagation velocity ranging from 0.22 to 4.3 mm/s depending on titanium content, and heating and cooling rates of 300–2000 °C/s and 3 °C/s during synthesis. The synthesized powders exhibited a bimodal particle size distribution, with ~90% of particles below 25 μm and a D50 of 5.38 μm. Post-synthesis densification via spark plasma sintering (SPS) at 1250 °C under 45 MPa yielded dense bulk samples, which exhibited a high relative density and high Vickers microhardness of 1270 ± 35 HV10 attributed to fine TiC dispersion and secondary carbide formation. Thermogravimetric analysis performed under air flow with a heating rate of 20 °C/min showed enhanced thermal stability for both the powder and the sintered bulk. These findings demonstrate the efficacy of SHS for rapid, energy-efficient fabrication of high-entropy composites and underscore the critical role of composition in tailoring their structural and mechanical properties. Full article

Despite significant interest in their functional properties, the mechanical behavior of high-entropy oxides (HEOs) is not well studied, particularly at elevated temperatures. Bulk (Co,Cu,Mg,Ni,Zn)O (transition metal (TM)-HEO) samples were deformed under compression at applied stresses and temperatures ranging from 5 to 31 MPa and 600 to 850 °C, respectively. All of the deformation conditions result in creep stress exponents of n < 3, indicating that TM-HEO exhibits superplastic deformation. A transition from structural to solution-precipitation-based superplasticity is observed during deformation above 650 °C. Additionally, TM-HEO exhibits shear-thickening behavior when deformed at stresses above 9 MPa. The formation and behavior of a Cu-rich tenorite secondary phase during deformation is identified as a key factor underpinning the deformation mechanisms. The microstructure and phase state of TM-HEO before deformation also influenced the behavior, with finer grain sizes and increasing concentrations of Cu-rich tenorite, resulting in the increased prevalence of solution-precipitation deformation. While complex, the results of this study indicate that TM-HEO deforms through known superplastic deformation mechanisms. Superplasticity is a highly efficient manufacturing method and could prove to be a valuable strategy for forming HEO ceramics into complex geometries. Full article

Transparent CAD/CAM monolithic ceramics are increasingly used in dentistry due to their combination of high strength, esthetics, and durability, achieved through high yttria content and multilayered systems. This study evaluates the mechanical behavior of four widely used CAD/CAM ceramics, correlating their performance with microstructural characteristics. Bar-shaped specimens (n = 10 per material, for each test) of ZOLID^® FX ML (ZF), IPS E.MAX^® CAD (MC), E.MAX^® ZIRCAD (ZM), and KAT-ANA^® STML (KS) (all A2 shade) were prepared and sintered according to manufacturers’ protocols. Flexural strength and elastic modulus were measured using three-point bending, and Vickers hardness was determined separately. Statistical normality was confirmed with the Kolmogorov–Smirnov test. Flexural strength ranged from 252.8 ± 39.8 MPa (MC) to 547.6 ± 125.7 MPa (ZM), elastic modulus from 65.8 ± 6.5 GPa (MC) to 94.1 ± 5.8 GPa (KS), and hardness from 4.2 ± 0.2 GPa (MC) to 9.6 ± 0.6 GPa (ZF). High-elastic-modulus materials (KS, ZM) can better resist deformation under occlusal loads, improving long-term stability of posterior crowns, bridges, and implant-supported restorations. High hardness (ZF) provides superior wear resistance and preserves occlusal anatomy over time, making it suitable for thin-shell restorations and high-stress functional surfaces. Materials with lower modulus and hardness (MC) are more suitable for intra-coronal restorations or thin veneers where stress shielding and material compliance are advantageous. These findings support material selection based on mechanical demands, and further clinical studies are needed to confirm long-term performance. Full article

The utilisation of magnesium oxide-based binders (M) as an alternative to hydrated calcium silicate materials is a promising avenue for binding methodologies. However, the efficacy of using silica fume (S) as a co-binder with magnesium oxide in sulphate soil stabilisation, along with their ideal blending ratio, has yet to be unveiled. Therefore, an array of artificial sulphate soil specimens was fabricated, each featuring varying combinations of magnesium oxide and silica fume. These specimens were subsequently subjected to comprehensive testing, including unconfined compressive strength (UCS) test, linear expansion test, thermogravimetric analysis, and X-ray diffraction analysis. The outcomes demonstrated that the co-utilisation of silica fume and magnesium oxide significantly improves the compressive strength and linear expansion of sulphate soil, and such an improvement was more efficacious at a stoichiometric amount of 5% magnesium oxide and 5% silica fume (5M5S). This outperforming threshold, characterised by the highest UCS (1834 kN/m²) and minimal expansion (0.2%), occurred through the consumption of surplus brucite and the formation of further magnesium silicate hydrate. Full article

Sulfate soil stabilisation, while offering technical benefits for infrastructure, is a challenging process, complicated by the nucleation of ettringite, an expansive mineral that can cause soil deterioration. This study was undertaken to elucidate the synergistic effect of lime and metakaolin on the physico-mechanical performance of high-sulfate-bearing soil. The binder content in the stabilised specimens was fixed at 20 wt%, and metakaolin was used to partially substitute lime at different substitution levels. The physico-mechanical investigation revealed that supplementation of lime with metakaolin had a promotional effect on the unconfined compressive strength and swelling potential. The threshold of this effect was obtained by a binary blend of 7.5L–12.5MK, where the UCS was increased fourfold, while the swelling potential was reduced to a near-zero magnitude of 0.33%. This superior performance is due to the fineness and high reactivity of metakaolin, as both limit the nucleation of ettringite and promote the neoformation of further hydrated compounds, thus yielding a denser interlocked system and increasing its resistance to water soaking. Full article

Garnet-type Li₇La₃Zr₂O₁₂ (LLZO) is a solid electrolyte candidate for ASSLBs, owing to its wide electrochemical window and intrinsic safety. Yet phase-pure LLZO remains difficult because secondary phases form, and the transition towards the tetragonal phase, aliovalent doping, mitigates these issues. Still, the phase formation pathway is not fully understood. Here, we present comparative in situ and ex situ studies of Nb- and Ta-doped LLZO (LLZNO and LLZTO) that were synthesized by a solid-state reaction. In situ/ex situ XRD reveals that the lithium precursor dictates the reaction path: differing decomposition temperatures of the lithium precursor define reaction windows that control cubic-phase purity and particle morphology. In air, limited Li diffusion favors oxycarbonates and pyrochlore, necessitating 950–1050 °C to achieve phase-pure cubic LLZO. Under N₂, faster Li availability and diffusion enable uniform nucleation and a route to cubic LLZO without detectable secondary phases. These findings demonstrate the coupled effects of temperature, precursor, dopant, and atmosphere, guiding process optimization and scalable production. Full article

The great city of Mayapan has experienced a technological change in pottery making, and our results confirm a shift in the raw materials and possibly the potters’ knowledge about them. The dynamics of change during the Postclassic period in the Maya area are reflected in the material changes used to make pottery. A comprehensive analysis was conducted on a collection of 248 pottery items from the archaeological site of Mayapán in Yucatán, Mexico, dating from the Middle Preclassic to Postclassic periods (700 BC–1500 CE). Non-invasive methods were used for the entire pottery set, including X-ray fluorescence (XRF) and fiber-optic reflectance spectroscopy (FORS). Additionally, for a representative subset, minimally invasive techniques such as inductively coupled plasma optical emission spectrometry (ICP-OES) and laser-induced breakdown spectroscopy (LIBS) were employed. The resulting data enabled the identification of materials used in the pottery’s manufacture. The elemental composition of the objects was determined, revealing correlations between elements such as Si with Al that yield a $R^2$ factor of 0.94. The results indicate the presence of smectite clays, carbonates, and iron oxides. The results show that a higher proportion of carbonates was found in the pieces from the Postclassic period compared to those from the Preclassic period, which may be associated with a change in the manufacturing process. Likewise, the Postclassic pieces are distinguished by a greater contribution of the Mg-OH signal, unlike the Preclassic and Classic, which show a greater contribution of the Al-OH group. The implications for the technological knowledge of the potters suggest the use of different technologies across various periods and material changes driven by shifts in political and economic relations in the city and the northern plains. Full article

Fine powders of erbium niobate-tantalates ErNb_xTa_1−xO₄ (x = 0; 0.1; 0.3; 0.5; 0.7; 0.9; 1) have been synthesized by the liquid-phase method in this study. Ceramic samples have been prepared using conventional sintering from these powders. Rietveld refinement of XRD patterns of polycrystals determined the phase composition and clarified the parameters of the phase structure of ErNb_xTa_1−xO₄ solid solutions depending on the Nb/Ta ratio. The morphological features of the microstructure of erbium niobate-tantalate ceramics have been studied. Their mechanical properties, strength characteristics (Young’s modulus, microhardness) and critical stress intensity factor of the first kind K_IC have been estimated. The photoluminescent properties of ceramic solid solutions of erbium niobate-tantalates depending on the composition have been studied. Dark and photoinduced toxicity of finely dispersed ErNbO₄ powders have been studied in relation to Gram-positive, Gram-negative and spore-forming microorganisms. The best indicators of antibacterial activity of ErNbO₄ have been demonstrated in relation to Gram-positive cells of Micrococcus sp. The discovered properties open up the possibility of not only traditional use as functional materials, but also the use of these materials for disinfection of surfaces, water and biological tissues. Full article

Background: Maxillomandibular bone defects present a complex challenge in regenerative medicine due to anatomical and functional intricacies. Calcium phosphate (CP)-based biomaterials have emerged as promising bone graft substitutes due to their biocompatibility, osteoconductivity, and bioactivity. Aim: This Review highlights recent clinical and experimental advancements in CP-based biomaterials for maxillomandibular bone regeneration, bridging the gap from bench to bedside. Method: An in vitro, in vivo, and clinical literature review was conducted to evaluate the performance of CP ceramics, including hydroxyapatite (HA), tricalcium phosphate (TCP), biphasic ceramics, and novel composites with polymers, growth factors, and nanoparticles. Results: Calcium phosphate-based biomaterials demonstrate excellent bone regeneration potential, with Beta-tricalcium phosphate (β-TCP) and HA being the most widely utilized. Composite scaffolds and 3-dimensional (3D)-printed constructs show enhanced mechanical properties and biological integration. Clinical trials have confirmed the safety and efficacy of CP-based materials, yielding promising outcomes in osteoconduction and defect healing. However, limitations persist regarding mechanical strength and long-term degradation profiles. Conclusions: CP-based biomaterials offer significant clinical promise for maxillomandibular bone regeneration. Continued advancements in scaffold design and biofunctionalization are crucial for overcoming current limitations and fully realizing their therapeutic potential. Full article

NiO-based hole-transport layers are crucial for high-efficiency perovskite solar cells. An industrial deposition method of NiO films is magnetron sputtering using ceramic targets. NiO targets doped with Li contents at 1%, 3%, and 5% were designed, and the doping contents and sintering temperatures were investigated. All the targets have a face-centered cubic phase, dense microstructure, and an average size of a few microns. The NLO targets sintered at an optimal temperature of 1400 °C exhibited high relative density (>98%) and low resistivity (<6 Ω∙cm). These results pave the way for depositing NiO-based hole-transport layer by magnetron sputtering. Full article

This work presents a comprehensive study on the synthesis and application of Al₂O₃ fibers derived from an ammonium aluminum carbonate hydroxide (AACH) precursor. Through a hydrothermal route, the influence of critical synthesis parameters, including aluminum nitrate and urea concentrations, reaction temperature and time, and stirring conditions, on fiber morphology and aspect ratio was systematically investigated. The as-synthesized AACH fibers were subsequently converted into thermodynamically stable α-alumina fibers via controlled annealing. These high-aspect ratio alumina fibers were incorporated into polydimethylsiloxane (PDMS) to produce electrically insulating, thermally conductive composites. The thermal performance of fiber-filled composites was benchmarked against that of particle-filled counterparts, with the former exhibiting significantly enhanced thermal conductivity. Furthermore, the dielectrophoretic alignment of alumina fibers led to an additional increase in thermal conductivity, underlining the importance of high-aspect ratio fillers. This study uniquely combines the controlled synthesis of alumina fibers with their incorporation and alignment in a polymer matrix, presenting a novel and effective approach for engineering anisotropic, thermally conductive, and electrically insulating composite materials. Dielectrophoretic alignment of α-Al₂O₃ fibers synthesized through optimized hydrothermal conditions and incorporated into PDMS composites deliver over 95 % higher thermal conductivity than spherical fillers. Full article

Barium strontium titanates (Ba_1−xSr_xTiO₃, BST) with varying barium-to-strontium ratios were synthesized by the solid-state route (SSR) as well as by the sol–gel process (SGP). In the case of the SSR, the strontium amount x was varied from 0.0 to 0.25 in 0.05 steps, due to the enhanced synthetic effort, and in the case of the SGP, x was set only to 0.05, 0.15, and 0.25. The resulting properties after synthesis, calcination, and sintering, like particle size distribution, specific surface area, particle morphology, and crystalline phase were characterized. The expected tetragonal phase, free from any remarkable impurity, was found in all cases, and irrespective of the selected synthesis method. Pressed pellets were used for the measurement of the temperature and frequency-dependent relative permittivity enabling the estimation of the Curie temperatures of all synthesized BSTs. Irrespective of the selected synthesis method, the obtained Curie temperature drops with increasing strontium content to almost identical values, e.g., in the case of x = 0.15, a Curie temperature range 95–105 °C was measured. Thin BST films could be deposited on different substrate materials applying electrophoretic deposition in a good and reliable quality according to the Hamaker equation. The properties of the BSTs obtained by the simpler solid-state route are almost identical to the ones yielded by the more complex sol–gel process. In future, this result allows for a possible wider usage of BST perovskites for ferroelectric and piezoelectric devices due to the easy synthetic access by the solid-state route. Full article

We synthesized the current evidence from the literature and conducted a 2 × 3 factorial experiment to quantify the impact of thermocycling on the Vickers microhardness (HV) of dental CAD/CAM materials: VITA ENAMIC (VE, polymer-infiltrated ceramic network) and CERASMART (CS, nanofilled resin-matrix). Sixty polished specimens (n = 10 per Material × Cycles cell; 12 × 2 × 2 mm) were thermocycled at 5–55 °C (0, 10,000, 20,000 cycles; 30 s dwell, ≈10 s transfer) and tested as HV0.3/10 (300 gf, 10 s; five indentations/specimen with standard spacing). Assumptions regarding the model residuals were met (Shapiro–Wilk W ≈ 0.98, p ≈ 0.36; Levene F(5,54) ≈ 1.12, p ≈ 0.36), so a two-way ANOVA (Type II) with Tukey’s HSD post hoc (α = 0.05) was applied. VE maintained consistently higher HV than CS at all cycle levels and showed a smaller drop from baseline: VE (mean ± SD): 200.2 ± 10.8 (0), 192.4 ± 13.9 (10,000), and 196.7 ± 9.3 (20,000); CS: 60.8 ± 6.1 (0), 53.4 ± 4.7 (10,000), and 62.1 ± 3.8 (20,000). ANOVA revealed significant main effects from the material (η²p = 0.972) and cycles (η²p = 0.316), plus a Material × Cycles interaction (η²p = 0.201). Results: Thermocycling produced material-dependent changes in microhardness. Relative to baseline, VE varied by −3.9% (10,000) and −1.7% (20,000), while CS varied by −12.2% (10,000) and +2.1% (20,000); from 10,000→20,000 cycles, microhardness recovered by +2.2% (VE) and +16.3% (CS). Pairwise comparisons were consistent with these trends (CS decreased at 10,000 vs. 0 and recovered at 20,000; VE only showed a modest change). Conclusions: Thermocycling effects were material-dependent, with smaller losses and better retention in VE (PICN) than in CS. These results align with the literature (resin-matrix/hybrids are more sensitive to thermal aging; polished finishes mitigate losses). While HV is only one facet of performance, the superior retention observed in PICN under thermal challenge suggests the improved preservation of superficial integrity; standardized reporting of aging parameters and integration with wear, fatigue, and adhesion outcomes are recommended to inform indications and longevity. Full article

This study reports the development of electrospun poly(methyl methacrylate) (PMMA) fiber mats incorporating ibuprofen (IBU)-intercalated layered double hydroxides (LDH) for enhanced transdermal drug delivery systems (TDDS). IBU, in its anionic form, was successfully intercalated into LDH, which possesses anion exchange capabilities, and subsequently embedded into PMMA fibers via electrospinning. In vitro drug release experiments demonstrated that UPMMA–LDH–IBU fibers exhibited significantly higher IBU release than PMMA–IBU controls. This enhancement was attributed to the improved hydrophilicity and water absorption imparted by the LDH, as confirmed by contact angle and water uptake measurements. Furthermore, artificial skin permeation tests revealed that the UPMMA–LDH–IBU fibers maintained comparable release rates to those observed during buffer immersion, indicating that the rate-limiting step was the diffusion of IBU within the fiber matrix rather than the interface with the skin or buffer. These findings highlight the critical role of LDH in modulating drug release behavior and suggest that UPMMA–LDH–IBU electrospun fiber mats offer a promising and efficient platform for advanced TDDS applications. Full article

This study investigated the effect of piranha solution etching duration on the shear bond strength of zirconia ceramics bonded to resin cement, comparing it to conventional sandblasting treatment. Fifty fully sintered zirconia specimens (6.0 mm diameter, 4.0 mm thickness) were prepared and randomly divided into five groups (n = 10): sandblasting control and piranha solution treatment for 1, 2, 3, and 4 min. Piranha solution was prepared by mixing 98% H₂SO₄ and 35% H₂O₂ in a 3:1 ratio. All specimens were bonded to resin composite cylinders using dual-cure resin cement. Shear bond strength testing was performed using a universal testing machine at a 0.5 mm/min crosshead speed. Failure modes were analyzed using a stereomicroscope and classified as adhesive, cohesive, or mixed failures. One-way ANOVA revealed significant differences between groups (p < 0.05). Tukey’s post hoc test showed that 1-min piranha treatment produced significantly lower bond strength (7.64 ± 2.02 MPa) compared to all other groups. The 2-min (15.17 ± 2.79 MPa), 3-min (14.99 ± 3.27 MPa), and 4-min (18.34 ± 3.15 MPa) piranha treatments showed no significant differences compared to sandblasting (15.41 ± 2.61 MPa). Failure mode analysis revealed 100% adhesive failures for the 1-min group, while all other groups showed 80% adhesive and 20% mixed failures. Piranha solution treatment duration significantly affected zirconia bonding performance. While 1-min treatment proved inadequate, 2–4 min treatments achieved bond strengths comparable to sandblasting. The findings suggest that piranha solution treatment for 2–4 min represents a viable alternative to sandblasting for zirconia surface preparation, with the 2-min protocol being the most efficient choice for clinical application. Full article

Translucency and color stability are key factors for the long-term success of dental ceramics. The aim was to compare the translucency parameter (TP) and color stability (ΔE) of CAD/CAM ceramics, including a lithium disilicate (E; IPS e.max CAD), a zirconia-reinforced lithium-silicate (S; VitaSuprinity), and a zirconia-based ceramic (Z; Ceramill Zolid HT+), before and after low-grade hydrothermal aging (134 °C and 2 bars for 20 h). Ninety disks (n = 30/group, A2, 1.2 ± 0.02 mm) were fabricated and their L*, a*, and b* values were recorded against black and white backgrounds to calculate TP, contrast ratio (CR), and opacity (OP). ANOVA, Bonferroni post hoc, and paired t-tests (α = 0.05) showed that after aging, the Z group showed ↓L and ↑a values; the E group showed ↓L with ↑ a and b; and the S group showed only ↑a. All ceramics exhibited ΔE values below the clinical acceptability threshold of 3.7. E presented the highest TP, whereas Z demonstrated the highest CR and masking ability. Aging significantly increased CR and OP but did not alter TP. Within the limitations of this study, all tested ceramics maintained clinically acceptable shade stability and translucency, with E showing superior initial translucency and Z offering improved masking potential. Full article

In this paper, 316 stainless steel/TiC coatings with different LaB₆ contents (0%, 2%, 4%, 6%) were prepared on the surface of 45 steel by laser cladding technology. The effects of the LaB₆ content on the phase composition, microstructure, microhardness, and wear resistance of the coatings were studied. The results show that without the LaB₆ addition, the coating is composed of Austenite and TiC phases, with defects such as pores and cracks, and the microstructure is mainly equiaxed grains. With the addition of LaB₆, Fe-Cr phases are formed in the coating, and the microstructure transforms into columnar grains and dendritic grains. The grains are first refined and then coarsened, among which the coating with 4% LaB₆ (C4) has the smallest grain size. The experimental results indicate that the microhardness of the coatings first increases and then decreases with the increase in the LaB₆ content, and the C4 coating has the highest microhardness (594HV_0.2). The wear rate shows the same variation trend. The C4 coating has the lowest wear rate and the best wear resistance. This is attributed to the synergistic effect of the fine grain strengthening and TiC particle dispersion strengthening. Full article

The mass transfer phenomenon of contained impurities causes differences in the morphologies, densification processes, and heat resistance of ceramics. Of these, in this paper, differences in the heat resistance of ceramic fibers are discussed. Third-generation SiC polycrystalline fibers demonstrated excellent heat resistance. However, at temperatures above 1800 °C, sintered fiber (Tyranno SA) and non-sintered fiber (Hi-Nicalon Type S) showed remarkable differences in heat resistance. At temperatures above 1800 °C, the non-sintered fiber underwent structural changes, including the formation of a surface carbon layer and abnormal SiC grain growth, whereas the sintered fiber maintained its stable polycrystalline structure. Until now, these differences and a detailed description of them have not been discussed. Here, we first explain the dramatic differences in heat resistance that occurred at high temperatures in relation to the mass transfer of excess carbon. Our findings should be widely used for the development of much more stable structures and for the long-term use of materials at higher temperatures in applications such as airplane engines and turbines. Full article

Binary oxide ceramics have emerged as key materials in solar energy research due to their versatility, chemical stability, and tunable electronic properties. This study presents a comparative analysis of seven prominent oxides (TiO₂, ZnO, Al₂O₃, SiO₂, CeO₂, Fe₂O₃, and WO₃), focusing on their functional roles in silicon, perovskite, dye-sensitized, and thin-film solar cells. A bibliometric analysis covering over 50,000 publications highlights TiO₂ and ZnO as the most widely studied materials, serving as electron transport layers, antireflective coatings, and buffer layers. Al₂O₃ and SiO₂ demonstrate highly specialized applications in surface passivation and interface engineering, while CeO₂ offers UV-blocking capability and Fe₂O₃ shows potential as an absorber material in photoelectrochemical systems. WO₃ is noted for its multifunctionality and suitability for scalable, high-rate processing. Together, these findings suggest that binary oxide ceramics are poised to transition from supporting roles to essential components of stable, efficient, and environmentally safer next-generation solar cells. Full article