Search Results (363)

Polymer-derived ceramics (PDCs) technology has been established for over five decades as a versatile route for the fabrication of advanced bioceramic materials. However, conventional processing routes for bioceramics, such as melt-quenching and sol–gel methods, still present significant limitations, including high processing temperatures, limited compositional flexibility, long processing times, and difficulties in fabricating complex and highly porous structures required for biomedical applications. In this context, increasing attention has been devoted to polymer-derived ceramics as an alternative approach for the fabrication of bioceramic materials. In this approach, preceramic polymers are converted into ceramic phases through thermal treatment in air or inert atmosphere (e.g., nitrogen), enabling low-temperature processing, high compositional flexibility, and precise control over phase evolution and microstructure. These features make the polymer-derived Ceramic route particularly attractive for the fabrication of complex and functional bioceramic architectures. This review provides an overview of the polymeric precursors employed for the synthesis of Polymer Derived Ceramic-based bioceramics, with particular emphasis on inorganic polymers, typically characterized by a siloxanic backbone, and the mechanisms governing their ceramization behavior. Special attention is given to emerging trends, including the integration of polymer-derived ceramics with additive manufacturing techniques and the development of functional systems for biomedical applications. Full article

The advancement of electrochromic devices, including smart windows, is important for improving energy efficiency in modern society. Nickel oxide thin films are key functional materials in this technology and have attracted significant attention due to their electrochemical activity and optical properties. However, existing theoretical studies have primarily focused on crystalline NiO, while systematic understanding of Li⁺ diffusion mechanisms in amorphous NiO remains limited. In this work, first-principles calculations combined with second-generation Car–Parrinello molecular dynamics simulations and the melt-quenching method are employed to construct amorphous NiO models with varying oxygen content, enabling investigation of oxygen-dependent Li⁺ diffusion behavior. The results show that the Li⁺ diffusion coefficient increases with increasing oxygen content, accompanied by a reduction in diffusion barriers. Analysis of local structural environments further reveals that Li coordination with under-coordinated Ni–O polyhedra plays a key role in facilitating ion migration, providing atomistic insight into the observed diffusion trends. This study establishes a structure–diffusion relationship in amorphous NiO and provides atomistic understanding of how oxygen stoichiometry modulates Li⁺ transport behavior in electrochromic materials. Full article

Zinc–antimony–boro–germanate glasses highly doped with Sm₂O₃ were synthesized by the conventional melt-quenching method. Their structural, optical, and luminescent properties were systematically investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV–Vis (DR-UV–Vis), and photoluminescence (PL) spectroscopy. XRD analysis confirmed the amorphous nature of all prepared samples. XPS measurements were used to examine the surface chemical composition of the Sm₂O₃-doped glasses, with particular focus on verifying samarium incorporation and identifying its oxidation state after synthesis, since Sm ions act as the luminescent centers in these materials. For the sample containing the highest Sm₂O₃ concentration, the DR-UV–Vis spectrum exhibited ten absorption bands assigned to intra 4f electronic transitions. Based on these data, the nephelauxetic and bonding parameters were determined, indicating that increasing Sm₂O₃ content enhances the ionic character of the bonds within the glass network. PL spectra revealed three characteristic emission bands associated with Sm³⁺ luminescent centers. The emission intensity reached a maximum at 3 mol% Sm₂O₃, while further increases in samarium content led to luminescence quenching. The most intense emission band was in the yellow–orange region of the visible spectrum, highlighting the potential of these materials for yellow–orange-emitting solid-state laser applications. The excitation spectra show that the optical response is strongly dependent on concentration, with a sample doped with 3 mol% Sm₂O₃ exhibiting the highest excitation efficiency. The dominant excitation band centered near 402 nm, together with weaker bands in the blue region, indicating that these glasses are promising candidates for near-UV-pumped orange-emitting photonic devices. Full article

The preparation of new magnetic materials is important because of their potential application in various electronic components. In the present work, the synthesis of glass-crystalline materials in the system Na₂O-MnO-SiO₂-Fe₂O₃ prepared by applying melt-quenching is reported. The phase composition as studied by X-ray diffraction and Raman spectroscopy reveals the precipitation of monophase Mn_xFe_3−xO₄ based solid solutions. The microstructure is studied by scanning electron and optical microscopy and shows bulk crystallization and the presence of polygon-shaped as well as of dendritic crystals, depending on the iron oxide concentration and used raw materials. Mössbauer spectra show that in the amorphous matrix the Fe ions are mainly present as Fe³⁺ in tetrahedral coordination and as Fe³⁺ in a solid solution with the composition Mn_xFe_3−xO₄. The simultaneous presence of MnFe₂O₄ (jacobsite) and a Mn-containing solid solution based on Fe₃O₄ (magnetite) is suggested. The room temperature magnetic properties were studied by vibrating sample magnetometer and reveal ferrimagnetic properties for all investigated glass-crystalline materials. Full article

The article investigates the dielectric and conductive properties of the polar α-phase of Na₃Fe₂(PO₄)₃ polycrystals synthesized by solid-phase (sample type 1), melt (type 2), and melt-quenching (type 3) methods. To enable a rapid assessment of the dielectric properties of the polar α-phase of Na₃Fe₂(PO₄)₃, the thermo-polarization mobility parameter μ_Tp(T, E(ω)) was introduced. By studying the dielectric properties, it was concluded that the polar α-phase of type 1 samples consists of large and small dipoles and ordered sodium cations, which possess low values of μ_Tp(T, E(ω)), indicating the presence of strong interaction forces between the crystal lattice and the cationic part of the polycrystal. Additional studies of the samples’ conductivity confirm this conclusion. Studies of the polar α-phase of Na₃Fe₂(PO₄)₃ in type 2 samples have established that their structure contains dipoles and sodium cations with higher values of μ_Tr(T, E(ω)), and also exhibits higher conductivity than Type 1 samples. These data indicate a weakening of the interaction forces between the cationic and anionic components in type 2 polycrystals due to a partial increase in crystal symmetry. The results of studies of the polar α-phase of type 3 samples show that their structure contains dipoles and sodium cations with higher values of μ_Tr(T, E(ω)), and also exhibits higher conductivity than type 2 samples. It is concluded that the structure of type 3 samples is characterized by weak interaction forces between the cationic and anionic parts as a result of an increase in the symmetry of the polar α-phase of Na₃Fe₂(PO₄)₃, caused by sharply graded temperature conditions during the synthesis of polycrystals. By studying the dielectric properties of cathode materials, it is possible to obtain information on the extent of interactions between the cationic and anionic components in polycrystals. It is, therefore, appropriate to use this approach when investigating a wide range of new dielectric and ion-conducting materials. Full article

Biomedical Ti–Nb–Zr–Si alloys containing 12 and 18 wt.% Nb were fabricated by electron beam melting and subjected to thermomechanical processing, including forging, cross-helical rolling, and subsequent cooling or quenching. The effects of Nb content and processing route on phase composition, microstructure, and mechanical properties were systematically investigated using X-ray diffraction, scanning electron microscopy, and tensile testing. The results indicate that increasing Nb content promotes stabilization of the metastable α″ phase, leading to a significant reduction in elastic modulus. The Ti–18Nb–4Zr–1Si alloy exhibited a modulus of ~60 GPa after rolling, which further decreased to ~40 GPa after additional quenching. In contrast, the Ti–12Nb–4Zr–1Si alloy showed higher values of 76–94 GPa due to the predominance of the α′ phase. Both alloys demonstrated a favorable combination of strength and ductility. Microstructural analysis revealed the formation of silicides, whose type and morphology depend on Nb content and processing conditions. The Ti–12Nb–4Zr–1Si alloy predominantly contains (Ti,Zr)₅Si₃, whereas the Ti–18Nb–4Zr–1Si alloy exhibits complex silicides composed of (Ti,Zr)₅Si₃ and (Ti,Zr)₃Si phases. These results highlight the potential of controlling phase composition and silicide evolution to tailor mechanical properties, particularly the elastic modulus, for biomedical applications. Full article

Large-scale reuse of copper tailings can mitigate environmental hazards and recover strategic elements; this work investigates the feasibility of producing foam glass-ceramics with high copper-tailing content (>70 wt%) by tuning the CaO/SiO₂ ratio to couple melt viscosity and crystallisation. The comprehensive utilisation of these tailings helps mitigate environmental pollution and enhance resource efficiency. In this study, foam glass-ceramics with varying CaO/SiO₂ ratios were synthesised through melt quenching followed by foaming heat treatment. The effects of different CaO/SiO₂ ratios on the foaming behaviour, crystallisation, and microstructure were investigated using DSC, FTIR, viscosity, XRD, SEM, and CT. The results indicate that increasing the CaO/SiO₂ ratio disrupts the three-dimensional network structure of the glass, which lowers the glass viscosity and influences the bubble size and distribution in the foam glass-ceramics. Additionally, the increased CaO content promotes crystal precipitation and enhances the compressive strength of the foam glass-ceramics. At a CaO/SiO₂ mass ratio of 0.22, the foam glass-ceramics exhibited the lower bulk density (240 kg/m³) and thermal conductivity (0.07 W/m·K). The materials also demonstrated good water absorption and compressive strength. This study highlights the potential of using copper tailings in foam glass-ceramics to improve their overall performance, offering promising energy-saving and environmentally friendly solutions. Full article

To facilitate the development of low-cost LTCC substrate materials and the high-value utilization of industrial tailings, α-cordierite glass-ceramics with varying Na₂O additions were prepared from perlite tailings as the main raw material via the melt-quenching method followed by sintering-induced crystallization. The synergistic effects of sintering temperature and Na₂O addition on the parent glass structure, crystallization behavior, and properties were systematically investigated. The results demonstrated that the addition of Na₂O effectively depolymerized the degree of network polymerization of the parent glass, altered the crystallization pathway of cordierite crystal, and promoted the densification of glass-ceramics at lower sintering temperature. The calculations of crystallization kinetics revealed that the crystallization process of α-cordierite was mainly dominated by three-dimensional bulk growth, and its nucleation mechanism changed from “site saturation” to “continuous nucleation” with the increase of Na₂O addition. The α-cordierite glass-ceramics sintered at 850 °C with 0.6 wt.% Na₂O addition exhibited the optimal comprehensive properties, including low dielectric constant (5.82 @ 10 MHz) and dielectric loss (1.80 × 10⁻² @ 10 MHz), high flexural strength (147.3 MPa), a Vickers hardness (9.01 GPa), and suitable coefficient of thermal expansion (2.96 × 10⁻⁶ K⁻¹, close to Si). The glass-ceramics are expected to be an ideal candidate for low-cost LTCC substrate materials. Full article

This study develops a kinetic model that captures poly-ether-ether-ketone (PEEK) crystallization over a temperature $T$ window from glass transition ($T_g$) to melting ($T_m$) temperature, and across cooling rates from 5 to ~10³ °C/min. The framework is a parallel dual-Nakamura formulation whose isokinetic parameters {$k_i\left(T\right),n_i,w_i\left(T\right)$} are obtained from a bi-level non-linear regression of isothermal crystallization tests conducted using a flash-differential scanning calorimeter (FSC). The weight $w_i\left(T\right)$ partitions the faster primary and slower secondary crystallization and is represented by a physics-based analytical function that captures its dome-shaped temperature dependence. A maximum isothermally achievable enthalpy function is introduced so that the model predicts enthalpy $\Delta H\left(t\right)$ natively under arbitrary thermal profiles. To extend this isothermal backbone to non-isothermal conditions, two explicit cooling-rate-dependent scalars are introduced, $\omega \left(\dot{T}\right)$ and $\chi \left(\dot{T}\right)$, which shift $w_i\left(T\right)$ and limit attainable crystallinity at high cooling rates respectively. Finally, a rate-dependent induction time relation is added to adjust the onset of crystallization. Calibrating these rate functions against non-isothermal experiments, while keeping the isokinetic parameters fixed, yields a single isothermal–non-isothermal model that predicts $\Delta H\left(t\right)$ under arbitrary $T\left(t\right)$ profiles. Model performance is validated using an interrupted FSC experiment with a multi-segment cooling program that mimics a local transient thermal history of PEEK during additive manufacturing. The sample is cooled through successive constant-rate segments with intermittent quench–remelt cycles to probe the accumulated crystallinity along the path. Without additional fitting, the model predicts the measured enthalpy evolution with R² ≈ 0.95. The framework thus provides a practical route for predicting polymer crystallinity under processing-relevant thermal histories. Full article

Elastocaloric cooling, which leverages stress-induced phase transformation in shape memory materials, represents a sustainable and energy-efficient alternative to conventional vapor-compression cooling systems. Central to optimizing these materials is understanding how thermal processing history dictates phase formation, microstructure, and thermal properties. In this study, we investigated the (Ni₅₀Mn_31.5Ti₁₈)_99.8B_0.2 compound synthesized via vacuum induction melting and arc melting, followed by water quenching. Induction melting results in needle-like, boron-rich precipitates within the martensite lattice. In contrast, vacuum arc melting promoted precipitate growth at the grain boundaries. The vacuum arc melting sample exhibits ~82% martensite phase fraction, a near-ambient transformation temperature of ~277 K, a large transition entropy change of ~75 J·kg⁻¹·K⁻¹, and moderate thermal hysteresis of ~24 K. These results underscore the pivotal role of thermal history in tailoring phase stability and transformation thermodynamics, providing essential design guidelines for subsequent mechanical performance optimization in elastocaloric shape memory alloys for energy-efficient and sustainable thermal management applications. Full article

Glasses with compositions (52.5 − x/2)B₂O₃:(12.5 − x/2)SiO₂:25La₂O₃:5ZnO:5CaO:0.5Eu₂O₃:xWO₃, x = 0, 2.5, 5, 7.5, 10, 20 (mol%) were prepared by conventional melt-quenching method and investigated by X-ray diffraction analysis, DSC analysis, DR-UV-Vis spectroscopy and photoluminescence spectroscopy. Physical parameters like density, molar volume, oxygen molar volume and oxygen packing density were also determined. Their values, as well as DR-UV-Vis spectroscopy results, indicate that the tungstate ions incorporate into the base borosilicate glass as tetrahedral WO₄ and octahedral WO₆ groups. With increasing WO₃ content over 5 mol%, WO₆ units are progressively linked to each other by W-O-W bonds, leading to the formation of a more connected and homogeneous glass network. Glasses are characterized by a high glass transition temperature (over 650 °C) and good thermal stability. The emission intensity of the Eu³⁺ ion increases with the introduction of WO₃ due to the occurrence of non-radiative energy transfer from the tungstate groups to the active ion. The most intense luminescence peak observed at 612 nm suggests that the glasses are potential materials for red emission. Full article

Polymer–ceramic composites based on cyanate ester resins have attracted increasing attention for high-frequency electronic applications due to their low dielectric loss, thermal stability, and dimensional reliability; however, achieving a targeted dielectric constant while maintaining low loss remains a key challenge. In this study, transparent glass powders and BaTiO₃ ceramic fillers were incorporated into a cyanate ester matrix to systematically investigate structure–property relationships and optimize dielectric performance for antenna-related applications. Transparent glass powders were synthesized via a melt-quenching route and combined with submicron BaTiO₃ particles, while both fillers were surface-modified using 3-triethoxysilylpropyl isocyanate (TESPI) to enhance interfacial compatibility. Composite samples containing 5–30 wt% total filler were fabricated and characterized by XRD, FTIR, tensile testing, dielectric measurements, and SEM/EDX analyses. The results demonstrate that TESPI surface modification promotes strong interfacial bonding and homogeneous filler dispersion within the cyanate ester matrix. An optimal balance between mechanical integrity and dielectric performance was achieved at 15 wt% total filler loading (K3), exhibiting a dielectric constant close to 10 and the lowest dielectric loss (tan δ ≈ 0.0047 at 1 MHz). Microstructural observations confirm that excessive filler loading leads to agglomeration and increased dielectric loss. Overall, the combined use of transparent glass and BaTiO₃ fillers, together with effective interfacial engineering, enables precise tuning of dielectric properties in cyanate ester composites for high-frequency electronic applications. Full article

New hard tissue formation helps create a more stable seal in endodontic treatment. To achieve this, a novel class of endodontic sealers containing the pro-osteogenic element, strontium (within a BG), embedded in a polydimethylsiloxane matrix (Sr-PDMS) was produced. The properties of this sealer were compared with a commercially available bioactive endodontic sealer, Guttaflow Bioseal (GFBS). Glass was prepared via the melt quench method and incorporated into the GFBS matrix. Its physical properties were tested against the International Organisation for Standardisation (ISO) 6876. For biocompatibility assessment, dose–response proliferation of OCCM-30 cells was quantified by measuring DNA levels in varying concentrations of exogenous calcium and strontium, in culture media conditioned with the novel BG powder, and in sealer discs of the GFBS and novel Sr-PDMS. Two-way ANOVA followed by one-way ANOVA and the Bonferroni post hoc test were applied to the cell viability data. Both the GFBS and novel Sr-PDMS sealants demonstrated physical properties that met ISO 6876, but Sr-PDMS displayed greater radiopacity (p < 0.05), lower solubility, and increased setting time. Both sealants released ions into the immersion solution, with the additional release of Sr from the novel sealer. GFBS displayed evidence of apatite formation. As expected, high concentrations of BG-conditioned media were cytotoxic, but the levels released by the BG in the Sr-PDMS were not cytotoxic with 1:000 dilution and resulted in significantly increased (p < 0.01) cell proliferation compared to the control group. Full article

Four compositions of rapidly quenched ribbon brazing alloys based on Ag–Cu–Ti (Ag–26.5Cu–1.5Ti, Ag–25Cu–5Ti) and Ag–Cu–Zr (Ag–26.5Cu–1.5Zr, Ag–25Cu–5Zr) systems were produced. Initial ingots were synthesized by arc melting. Rapidly solidified ribbons, 50–100 μm thick, were then fabricated from homogenized ingots using a “Crystall-702” facility. A comparative analysis of the microstructure and phase composition of both the ingots and ribbons was conducted using scanning electron microscopy and X-ray diffraction. The analysis revealed the presence of Cu₄Ti and CuTi intermetallic compounds in the Ag–Cu–Ti alloys, and AgCu₄Zr and Zr₂Cu in the Ag–Cu–Zr alloys. Rapid quenching was found to produce metastable structures and significantly refine the intermetallic phases. Microhardness measurements of the ingot and ribbon states demonstrated a substantial influence of the processing route on the mechanical properties. The tensile strength of the ingots was also evaluated. The wetting angles of the rapidly quenched alloy melts on 99% Al₂O₃ (alumina) ceramic substrates under vacuum were determined. All produced ribbons, except for the Ag–26.5Cu–1.5Zr composition, demonstrated adequate wettability. Thus, these materials are considered promising for further research into heat-resistant metal–ceramic joints. Full article

Lead borophosphate zinc barium glass systems doped with different concentrations of Dy₂O₃ (0.5–2.0 mol%) were fabricated using the traditional melt-quenching method. The non-crystalline nature of the synthesized glass samples was verified through X-ray diffraction (XRD) analysis, which exhibited the characteristic absence of sharp diffraction peaks. Morphological, structural, and vibrational properties were analyzed using scanning electron microscopy (SEM) and Fourier infrared transmission (FTIR) spectroscopy. Optical absorption, emission, and decay lifetime observations were recorded to evaluate the luminescence behavior of Dy³⁺ ions. Judd–Ofelt parameters (Ω₂, Ω₄, and Ω₆) were evaluated from the optical absorption spectra of all the prepared glass samples. The emission spectra revealed three dominant transitions in the visible region corresponding to the ⁴F_9/2 ⟶ ⁶H_15/2 (blue ~ 484 nm), ⁴F_9/2 ⟶ ⁶H_13/2 (yellow ~ 574 nm), and ⁴F_9/2 ⟶ ⁶H_11/2 (~663 nm) transitions. Radiative characteristics, including radiative transition probability (A_R), radiative lifetime (τ_R), and branching ratio (β_R), were calculated from the emission spectra. Among the investigated compositions, the host glass embedded with 1.0 mol% Dy₂O₃ demonstrated the maximum emission intensity was observed along with superior quantum efficiency (η = 91.68%). The chromaticity coordinates for this composition (x = 0.33, y = 0.41) are positioned close to the white-light region in the CIE 1931 chromaticity diagram. These findings suggest that incorporating 1.0 mol% of Dy₂O₃ yields the highest luminescence efficiency, making the present glass system a promising candidate for white-light-emitting and photonic device applications. Full article