To suppress the formation of oxygen-vacancy during hot isostatic pressing (HIP), we introduce ZrO2 powder-bed HIP (ZB-HIP) as a novel approach to fabricate MgGa2O4 transparent ceramics. The differences between the two HIP routes were systematically compared to establish the correlation among HIP processing, defect evolution, and optical properties. The results suggest that the strategy exerts no obvious adverse effect on densification during HIP, but effectively suppresses the formation of oxygen-vacancy, thereby reducing the initial defect concentration. Consequently, the optimum annealing temperature decreased from 925 to 875 °C, thereby limiting the growth of residual pores during annealing and preventing optical degradation, especially in the visible region. The annealed ZB-HIP ceramic achieved a high in-line transmittance of ∼74.1% at 600 nm, significantly higher than the ∼64.1% obtained for the corresponding HIP counterpart. The ZB-HIP strategy may provide an effective and scalable route for defect regulation in oxygen-sensitive transparent ceramics.

Partially stabilized zirconia ceramics are renowned for their excellent mechanical properties and are widely employed as advanced structural ceramics. However, their relatively low hardness limits their certain applications. In this work, guided by thermodynamic calculations, multicomponent oxide-monoboride-diboride composites with excellent mechanical properties were prepared by using nine transition metal oxides (groups IVB-VIB) and B4C as starting materials. Y2O3 was introduced in varying contents as a stabilizer for the (Hf, Zr)O2 oxide phase, and its effect on phase composition, microstructure, and mechanical properties was systematically investigated. At an optimal Y2O3 content, the composite achieved a Vickers hardness (4.9 N) of 23.07 +/- 0.57 GPa and simultaneously a Young's modulus of 384.42 GPa, significantly superior to conventional oxide ceramics. Their fracture toughness and flexural strength reached 5.71 +/- 0.50 MPa m1/2 and 570.80 +/- 19.96 MPa, respectively, higher than most of the typical high-entropy boride ceramics. Further increase or decrease in Y2O3 contents led to the reduced toughness and strength, primarily due to the diminished transformation of the tetragonal-(Hf, Zr)O2 phase during crack propagation. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Transparent MgAl2O4 ceramics are promising materials for transparent armor, infrared windows, and domes, yet their high optical quality is typically achieved using costly ultrafine nanopowders. This work demonstrated that the incorporation of Li (+) could significantly enhance the sinterability of MgAl2O4 with relatively large particle size. This enhancement is achieved by reducing the formation energy of Schottky defects and promoting oxygen vacancy generation at elevated temperatures. Despite their larger particle size (similar to 347 nm), Li0.125Mg0.75Al2.125O4 powders achieve pore closure during pre-sintering at similar to 1475 degrees C, comparable to that of ultrafine commercial S30CR powder (similar to 50 nm) and more than 100 degrees C lower than that required for MgAl2O4 powders of similar size. Consequently, fully dense Li0.125Mg0.75Al2.125O4 transparent ceramic with a high in-line transmittance of similar to 78% at 500 nm was obtained at a hot isostatic pressing temperature as low as 1500 degrees C. The transparent ceramics also exhibited an enhanced hardness of 14.7 GPa, attributed to a larger number of strong Al-O bonds, suggesting Li0.125Mg0.75Al2.125O4 as a promising candidate for advanced optical applications.

Silicon nitride (Si3N4) is an excellent candidate for engineering ceramics; however, its toughness and hardness remain fundamentally constrained by the inherent limitations arising from the incompatible alpha-phase (characterized by high hardness) and beta-phase (characterized by high toughness). Herein, we report the exploration of advanced Si3N4 ceramics enabled by an intergrown cluster microstructure, which achieves a synergistic enhancement in both toughness (10.2 +/- 0.3 MPa & centerdot;m1/2) and Vickers hardness (20.1 +/- 0.3 GPa). These synergistic properties represent the state-of-the-art among Si3N4 ceramics fabricated via liquid-phase sintering reported to date. The formation of columnar clusters is driven by a high-pressure-induced coarsening process. The established metastable growth mechanism may open an avenue for fabricating new-generation Si3N4 ceramics with superb performance.

ABSTRACT Pressure‐assisted sintering of high‐performance boron carbide (B 4 C) into complex shapes remains a significant challenge. In this study, a near‑net‑shape B 4 C hemisphere was successfully prepared by hot pressing using a specially designed mold. The uniform dispersion of nano‑Al 2 O 3 within the B 4 C matrix, achieved via a hydrothermal process, enhances both sinterability and mechanical properties. A pressure‐induced phase transformation from Al 2 O 3 to Al 18 B 4 O 33 is identified at applied pressures exceeding 40 MPa, which tailors the densification rate and determines the final phase assemblage. The as‑obtained hemisphere achieved full density, exhibited uniform thickness, and was free of internal defects, demonstrating a viable route to break the conventional performance–geometry trade‑off in B 4 C‑based ceramic components.

Developing hydrogen evolution reaction (HER) electrocatalysts with high activity in both acidic and alkaline media is of great significance for adapting to diverse electrolytic environments. In this study, MoSe2 and Ni3Se4 nanosheets were successfully composited on high-entropy M4C3Tx MXene (M = Ti, V, Mo, Nb, Ta) via a hydrothermal method, constructing a novel heterostructured catalyst. This design leverages the excellent conductivity and multielement synergistic effect of high-entropy MXenes, which not only facilitates electron transport but also provides a robust platform for the uniform distribution of MoSe2 and Ni3Se4 nanosheets, thereby exposing abundant active sites. Electrochemical tests indicate that the catalyst exhibits excellent HER performance in both 0.5 M H2SO4 and 1.0 M KOH electrolytes. Specifically, under acidic conditions, MoSe2/Ni3Se4/M4C3Tx shows an overpotential of only 67 mV at a current density of 10 mA & centerdot;cm-2 with a Tafel slope of 68.7 mV & centerdot;dec-1, while under alkaline conditions, the overpotential at 10 mA & centerdot;cm-2 is 73 mV with a Tafel slope of 77.8 mV & centerdot;dec-1. Moreover, the catalyst demonstrates excellent long-term stability in both acidic and alkaline media. This work provides a new strategy for designing efficient and stable HER catalysts suitable for harsh acid-base environments.

Transparent Y3Ga5O12 (YGG) ceramics possess promising application prospects in persistent, near-infrared, and mechanical luminescence fields. YGG transparent ceramics were successfully prepared using GeO2 as a sintering additive via air pre-sintering and hot isostatic pressing. At 90% relative density, the densification activation energy increased from 598 to 981 kJ/mol as the GeO2 content rose from 0 to 0.12 wt%. Through the analysis of sintering trajectory and grain boundary mobility, it was revealed that GeO2 effectively inhibited grain growth. The inhibition of densification and grain growth resulted from the decreased oxygen vacancy concentration due to Ge4+ substituting for Ga3+ sites in YGG lattices. YGG transparent ceramic with 0.06 wt% GeO2 exhibited an optimal in-line transmittance of 68.5% at 800 nm, while its optical band gap and refractive index (589 nm) were 3.99 eV and 1.913, respectively. This work offers an effective sintering approach for preparing gallium garnet transparent ceramics.

Multicomponent oxide ceramics yield great promises in next-generation thermal protection systems according to their high potential for thermal stability and ablation resistance, but their protective mechanisms remain unclear. In this study, the five multicomponent A6B2O17 (A = Zr, Hf; B = Nb, Ta) oxide ceramics with different atomic concentrations, respectively, at A- and B-sites, were prepared via a solid-state reaction with a rapid cooling process. Their phase, structural evolutions, and the properties under high-temperature treatment and dynamic ablations were investigated to reveal thermal stability and anti-ablation mechanisms. Only the (Hf1/2Zr1/2)6(Ta1/2Nb1/2)2O17 with equal molar ratio both at A- and B-sites maintained the A6B2O17 phase after heat treatment at 1773 K for 25 h; the other samples underwent phase separation behaviors. In addition, the (Hf3/4Zr1/4)6(Ta2/3Nb1/3)2O17 ceramic showed excellent ablation resistance (similar to 2500 K, 100 s) with the thinnest oxide layer. This property is attributed to the formation of "skeleton-filler phase" protective composite layer, as the (Zr, Hf)O2 "skeleton" owns high melting point and low volatility to resist thermal gas erosion, and the AnB2O2n+5 family fills defects and hinders the penetrations of O2. This study expects to offer design for advanced thermal barriers suitable for the next-generation hypersonic vehicles and reusable spacecraft.

A multi-phase multi-component carbide (Zr1/6Hf1/6V1/6Cr1/6Mo1/6W1/6)C0.6 was synthesized via hot-pressing sintering under 1650 degrees C-2000 degrees C at an interval of 50 degrees C for 1 h. A three-stage solid solution process is revealed: the elemental segregation, emergence of a multi-phase microstructure, and subsequent formation of a dual cubic phase carbide. Specifically, the elemental segregation dominates at 1650 degrees C-1700 degrees C. Subsequently, the (ZrHf)C-rich and (V(CrMoW))C-rich coupled with (CrMoW)C-rich phases emerge, with the latter exhibiting a hexagonal structure. This hexagonal phase then binds with (V(CrMoW))C-rich phase, resulting in a composite microstructure of (ZrHf)C-rich and (VCrMoW)C-rich phases. The sample sintered at 1900 degrees C possess higher Vickers hardness (23.3 GPa) and flexural strength (474 MPa) over that sintered at 1800 degrees C, primarily attributed to the solid solution strengthening. Conversely, the sample sintered at 1800 degrees C demonstrates superior fracture toughness (5.4 MPa & centerdot;m1/2), attributed to the crack deflection caused by the plate-like microstructure, effectively dissipating more fracture energy.

The nacreous layer of shells has become an excellent biomimetic template of materials due to its unique structure. Inspired by the highly complex multilayered structure of shells, biomimetic layered composite protective materials with outstanding strength, toughness, and impact resistance have been developed. As the hard phase in biomimetic pearlescent layered protective materials, ceramics suffer from inherent low toughness. Applying prestress proved to be an efficient method to enhance their toughness and impact resistance. In this study, prestressed biomimetic periodic laminated (TiB 2 -TiB)/Ti protective materials were fabricated with spark plasma sintering (SPS) technology under the conditions of 1450 degrees C and 30 MPa in an argon atmosphere. Moreover, both experimental and numerical simulation analyses were conducted to investigate their protective performance. Compared to non-prestressed protective materials, the prestressed constrained materials exhibited the significantly improved protective performance with reduced penetration depth, substantially lower residual velocity, and kinetic energy after impact. This study provided valuable insights into the structural design and performance optimization of other protective materials. (c) 2025 The Authors. Published by Elsevier B.V. on behalf of The Chinese Ceramic Society. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Based on large lattice distortion, a series of multi-component carbides (ZrHfVCrMoW)Cx was designed and synthesized via hot-pressing sintering under 30 MPa at 1800 degrees C for 1 h, with systematic investigation of composition-structure-property relationships using multi-scale characterization. The phase composition of all samples reveal multi-phase structure composed of (ZrHf)C-rich and (VCrMoW)C-rich phase. It is revealed that decreased carbon content gradually leads to the decline in thermal conductivity. While the mechanical evaluation demonstrates non-monotonic behavior: peak Vickers hardness (24.4 +/- 0.3 GPa) and flexural strength (520 +/- 12 MPa) at x = 0.7, contrasted with maximum fracture toughness (3.95 +/- 0.3 MPa & sdot;m1/2) at x = 0.8 attributed to synergistic effects of solid solution strengthening and vacancy-mediated lattice distortion. Furthermore, the phase stability of all samples is confirmed through annealing under 2000 degrees C/10 h, with the results exhibiting retained phase integrity and limited grain growth, suggesting well phase stability of multiphase configuration correlated with sluggish diffusion kinetics.

A synergistic enhancement in bending strength, hardness, and fracture toughness while maintaining low density in B 4 C ceramics remains a challenge. Herein, we propose to design a simple three‐layer symmetrical sandwich‐type laminated structure of B 4 C‐TiB 2 by imitating the nacre's structure, which effectively minimizes interfacial defects and achieves stronger interfacial bonding via reactive sintering using B 4 C, TiC, and B as starting materials. The simple symmetric design generates residual compressive stress in both outer layers and tensile stress in the middle layer. It has been found that the residual compressive stress can counteract external loads and lead to a remarkable improvement in hardness and bending strength. Furthermore, a rising R‐curve behavior is observed in the fracture toughness testing of laminated B 4 C‐TiB 2 ceramics, indicating superior resistance to crack propagation. Compared to monolithic ceramics, the as‐synthesized laminated B 4 C‐TiB 2 ceramic exhibits amazing comprehensive properties with a high hardness of 37.1 ± 0.4 GPa, bending strength of 834.3 ± 62.8 MPa, and fracture toughness of 5.0 MPa·m 1/2 . This work provides precise guidance for the design of impact‐resistant ceramics by offering an in‐depth understanding of how residual compressive stress affects mechanical properties.

(TiZrHfNbTaCr)Cx ceramics with different carbon contents were fabricated via carbothermal reduction (CTR) combined with spark plasma sintering (SPS) at 1900 to 2100 degrees C. The effects of carbon content and sintering temperature on Cr solubility, as well as the microstructure and mechanical properties, were systematically investigated. At 1900 degrees C, samples with low carbon contents form a single-phase solid solution with homogeneous elemental distribution; however, the Cr content within the grains (similar to 1 at.%) is significantly lower than that in samples with high carbon contents. In contrast, Cr3C2 at triple junctions of grain boundaries is detected in samples with high carbon contents. With increasing sintering temperature, the solubility of Cr increases (4 at.%) and the elemental distribution becomes more uniform, although Cr still shows a tendency to segregate along grain boundaries. Under conditions of lower carbon content and sintering temperature (1900 degrees C), the ceramics exhibit excellent comprehensive mechanical properties with the Vickers hardness of 22.2 GPa, flexural strength of 536 MPa, and fracture toughness of 4.32 MPa & centerdot;m1/2. Correspondingly, the dominant fracture mode transitions from transgranular to intergranular fracture.

High-entropy borides (HEBs) are emerging as promising candidates for extreme environmental applications due to their exceptional thermal stability, mechanical properties, and tunable electromagnetic properties. This study presents the first systematic investigation of rare-earth-doped deca-component highentropy borides, (TM0.9 RE0.1 )B2 , (TM = Zr, Hf, Nb, Ta, Ti, W, Cr, V, Mo and RE = Sc, Y, Gd, Dy, Ho, Er, Lu, Sm, Eu, Tm, Tb, Pr, Yb). Evaluations of multiple descriptors, including electron work function and mixing enthalpy, revealed that Sc-containing decaboride (HEB10-Sc) exhibits superior single-phase formation capability. In contrast, the widely used valence electron concentration parameter proved inapplicable due to identical outer-electron counts across rare-earth elements. Boro/carbothermal reduction (BCTR) experiments at 1650 degrees C, employing transition metal oxides, rare-earth oxides, and B4 C as precursors, demonstrated that Sc uniquely enables the formation of a single-phase diboride with nine Group IVB-VIB transition metals, unlike other rare-earth dopants. The phase evolution mechanism during the BCTR process was elucidated: ScBO3 , formed in situ during BCTR, exhibits greater reducibility resistance than the most refractory HfO2 , thereby suppressing polyboride formation (common in other rare-earth systems) and facilitating single-phase HEB10 formation. The resulting HEB10-Sc displays outstanding electromagnetic wave absorption performance, achieving a reflection loss (RL) of -35.3 dB at 10.6 GHz (3 mm thickness) and an effective absorption bandwidth of 4.7 GHz in the X and Ku bands. These findings underscore the critical role of rare-earth doping in tailoring the structural and functional properties of high-entropy borides, offering a pathway to design advanced multifunctional materials for extreme environments such as thermal protection and high-temperature electromagnetic absorption in aerospace and electronic applications. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

A novel silicon carbide (SiC) fiber-derived ceramic was successfully fabricated via SPS using SiC fibers as raw materials, which overcame the inherent brittleness, poor machinability, and low electrical conductivity of traditional SiC ceramics. The fracture surface displayed a typical zigzag crack propagation path with a fracture toughness reaching 6.11 MPa.m(1/2). The stress-strain curve exhibited a multistage fracture response, thereby effectively dissipating energy. The SiC fiber-derived ceramic achieved a high conductivity of 1510 S.m(-1) at 700 degrees C, while its thermal conductivity remained at a stable level of 39 W.m(-1).K-1. The enhanced electrical conductivity was attributed to the gradual graphitization of amorphous carbon within the SiC fibers during the sintering process, which resulted in the formation of a continuous conductive graphite network. In addition, the thermoelectric potential of the SiC fiber-derived ceramic was also evaluated. Despite this favorable trend in the Seebeck coefficient, the calculated zT values remained extremely low. Instead, it exhibits obvious potential as a high-temperature conductive structural material. This work effectively provided a new route for developing high performance SiC-based ceramics with integrated structural and functional properties.

Al2O3-Y3Al5O12 (Al2O3-YAG) eutectic ceramics with the refined and homogeneous microstructure were fabricated rapidly using a novel strategy of combustion synthesis chemical furnace, which combined self-propagation high-temperature heating method with a self-designed rapidly unidirectional solidification equipment. The microstructure, crystallographic orientation relationships and mechanical properties of Al2O3-YAG eutectics were investigated. The results show that the Al2O3-YAG eutectic ceramic features a complex homogeneous 'Chinese script' irregular morphology. The interfacial crystallographic orientation relationships between the Al2O3 and YAG phases are: [111] YAG & Vert;[1100] Al2O3 and (110) YAG & Vert;(1120) Al2O3. Moreover, transition from the irregular eutectic to colony structure was recognized in a cross-section taken 1 mm from the bottom of the Al2O3-YAG ingot. The colony structure consists of the regular lamellar-like or rod-like structure in the central zone and the coarse irregular structure in the boundary region. The relative density, Vickers hardness and fracture toughness of Al2O3-YAG eutectic are measured to be 98.2%, 21.1 GPa and 3.24 MPa m1/2, respectively. The superior fracture toughness is ascribed to the homogeneous and fine eutectic network structure which retards the crack propagation.

ABSTRACT Boron‐rich boron carbide (B 5.25 C) rather than stoichiometric B 4 C powder was synthesized via vacuum carbothermal reduction at 1400°C from boric acid and sorbitol. This value (5.25) remains constant even when the ratio of carbon to boron source (C/B) molar ratio in the raw materials varies in a large range from 1 to 3; furthermore, the C/B value could affect the particle size of as‐synthesized powders obviously. The maximum boron utilization efficiency was achieved at a C/B ratio of 1.75, yielding B 5.25 C powders with an average particle size of 1.80 ± 0.25 µm, free carbon and oxygen contents of 0.38 wt.% and 0.46 wt.%, respectively. The powders prepared under optimal conditions show good sinterability; after sintering at 1900°C under 60 MPa for 15 min by spark plasma sintering, fully dense boron carbide ceramics were obtained, in which ∼42% of their grains exhibit twins with a misorientation angle of 74.7° <01>, demonstrating good mechanical properties.

Traps with suitable depths and appropriate distributions are indispensable for optical information storage in persistent luminescence (PersL) materials. However, ZnGa2O4: Cr3+ fluorescent powders suffer from shallow trap depth and can hardly be regarded as candidates for storing optical information. In this study, ZnGa2O4:0.25 at% Cr3+ PersL transparent ceramics were prepared by pressureless sintering combined with hot isostatic pressing (HIP). The ceramics exhibit in-line transmittances of 69.1% at 0.7 & micro;m and 82.2% at 2.5 & micro;m. The initial afterglow intensity of the transparent ceramics is two orders of magnitude higher than that of the powders, and its duration is longer. Traps distributed in the range of 0.71-0.92 eV are suitable for optical information storage at room temperature. More oxygen vacancies and oxygen vacancy clusters were generated in the transparent ceramics due to the influence of the sintering process, which resulted in an increase in trap depth. The ceramics exhibit erasable and stable optical storage performance, with an information retention time exceeding 1 week. This study highlights the prospect of applying PersL transparent ceramics to optical information storage through trap regulation.

Biominerals possess the capability to encapsulate organic macromolecules or inorganic nanoparticles within their matrix crystals during the growth process. The robust interfacial interactions between guest nanoparticles and the host crystals contribute to the exceptional mechanical properties of biominerals. Inspired by this natural encapsulation process, vaterite microspheres incorporating green fluorescence protein-modified Escherichia coli (GFP-E. coli@vaterite) are synthesized. The encapsulation process involves the initial adhesion of amorphous calcium carbonate precursor onto the surface of E. coli, followed by progressive mineralization with growing vaterite crystals, thereby achieving the encapsulation of 14.6 wt% bacteria within vaterite microspheres. Subsequently, dense composite bulks are fabricated through cold sintering of the GFP-E. coli@vaterite powder at 100 degrees C under a pressure of 1 GPa. The resulting composites achieved flexural strength and fracture toughness of 69.9 MPa and 0.75 MPa center dot m1/2, representing 1.4-fold and 2.2-fold improvements over pure vaterite bulk (48.4 MPa and 0.34 MPa center dot m1/2), respectively. Notably, the GFP-E. coli@vaterite composite bulks maintained stable fluorescence for more than eighteen months, with minimal signal attenuation and a fluorescence lifetime exceeding 1.1 mu s. Our work provides an efficient approach to fabricate integrated structural and functional composites under low temperature conditions. This work also establishes a new direction in fluorescent marking technologies and demonstrates promising potential for practical implementation.

ABSTRACT Transparent lithium aluminum oxynitride (LiAlON) ceramics have attracted increasing attention because Li incorporation improves aqueous processability while modifying the crystal chemistry and microstructural evolution of conventional AlON. In this work, the mechanical reliability and thermophysical behavior of highly transparent Li 0.07 Al 2.76 O 3.64 N 0.36 ceramics were systematically investigated. Room‐temperature fracture behavior was systematically evaluated using Weibull statistics, subcritical crack growth (SCG) analysis, and strength–probability–time prediction. Thermophysical properties, including thermal expansion coefficient, specific heat capacity, thermal diffusivity, thermal conductivity, and temperature‐dependent Young's modulus, were measured over a wide temperature range. High‐temperature fracture strength and thermal shock resistance were further estimated using experimentally determined thermophysical parameters. The LiAlON ceramics exhibited a characteristic flexural strength of 254 MPa with a Weibull modulus of 4.33. Quantitative defect analysis indicated that surface machining damage, rather than residual porosity, dominated fracture initiation, suggesting a surface‐flaw‐controlled fracture behavior in the coarse‐grained microstructure. The SCG exponent was approximately 11, indicating moderate susceptibility to environmentally assisted crack propagation. Thermal conductivity remained slightly higher than that of conventional AlON despite Li incorporation, which is attributed primarily to reduced grain‐boundary phonon scattering associated with the coarse‐grained microstructure. Young's modulus decreased nearly linearly with temperature, and the predicted fracture strength remained approximately 190 MPa at 800°C. The present results suggest that the coarse‐grained microstructure simultaneously influences mechanical reliability and thermophysical performance through different microstructural pathways, highlighting the importance of balancing surface‐flaw tolerance and grain‐boundary scattering in the microstructural design of transparent structural ceramics for optical and high‐temperature applications.