SiC-ZrB2 multiphase ceramics exhibit excellent thermal stability, oxidation resistance, corrosion resistance, high hardness, and thermal shock resistance, making them promising candidate materials for high-temperature structural applications. The key to fabricating high-performance SiC-ZrB2 multiphase ceramics is to synthesize ultrafine composite powders with uniform dispersion and high sintering activity. In this study, SiC-ZrB2 composite powders were synthesized via an optimized carbothermal reduction method using silica sol, flake graphite, ZrO2, and H3BO3 as raw materials. The effects of calcination temperature (1400-1650 degrees C) on the phase composition, weight loss, and microstructure of the as-synthesized powders were systematically investigated. The optimized powder prepared at 1600 degrees C was selected for spark plasma sintering (SPS) at 1650-1850 degrees C, and the densification behavior and mechanical properties of the sintered ceramics were characterized. The results show that the carbothermal reduction reaction is essentially completed at 1600 degrees C, and SiC-ZrB2 composite powders with no obvious impurities can be obtained. The weight loss of the powders increases with rising calcination temperature, reaching 63.2% at 1600 degrees C, and the increment tends to slow down at higher temperatures, indicating that the reaction has reached a stable state. The powder synthesized at this temperature exhibits a homogeneous microstructure composed of ultrafine particles (50-100 nm) and abundant SiC whiskers, without obvious elemental segregation. The ceramics sintered by SPS at 1750 degrees C present the optimal mechanical properties: a relative density of 97.6%, Vickers hardness of 16.9 GPa, and fracture toughness of 7.5 MPa & sdot;m1/2.

Perovskite solid electrolytes hold considerable promise for all-solid-state lithium batteries, whereas the underlying cause of their low grain boundary conductivity remains elusive. In this study, we prepared perovskite Li0.32La0.56Fe0.01Ti1-xSbxO3 (where x = 0.02, 0.04, 0.06, 0.08, and 0.1) solid electrolytes by introducing Sb3 * for unequal valence substitution at the B-site. The electrical valence balance mechanism generates the Schottky defects, and the unequal valence substitution of Sb3 * facilitates the migration of lattice oxygen to the grain boundaries, which weakens the enrichment of positive charges at the grain boundaries, mitigates chemical composition discrepancies, structural distortions, and atomic rearrangements at the grain boundaries, and ultimately improves the grain boundary conductivity. An in-depth investigation of unit cell and grain boundary structures deduced a pivotal trade-off relationship between grain conductivity and grain boundary conductivity. At x = 0.06, the total electrical conductivity reaches 5.9 & times; 10-2 mS center dot cm-1 at 25 degrees C, which increased by 103% compared with the undoped samples. This study provides practical design strategies for further enhancing the grain boundary conductivity in perovskite solid electrolytes.

Lightweight u03B2-Li2TiO3 ceramics are promising microwave dielectrics for the large-scale deployment of 5.5G extremely large antenna arrays (ELAAs). However, their practical application is hindered by the limited Qu00D7f value (where quality factor Q = 1/dielectric loss (tanu03B4), and f represents the resonant frequency) and large positive temperature coefficient of resonant frequency (TCF), while the underlying phase transition and regulatory mechanisms remain elusive. Here, a unique monoclinicu2013cubic dual-phase architecture is constructed in Li2Ti1u2212x(Sc1/2Nb1/2)xO3 (LTSNx, 0 u2264 x u2264 0.5) ceramics. In situ structural characterizations reveal that the substitution-induced reduction in the phase transition temperature (Tc) and concomitant lattice distortion synergistically impede the reversed-phase transformation, stabilizing the high-temperature cubic phase at room temperature. Consequently, the inherent negative TCF of the cubic phase effectively compensates for the positive value of the monoclinic matrix, achieving exceptional temperature stability. Furthermore, the reconstructed superlattices and suppression of lattice defects significantly minimize dielectric loss. Of particular importance is that the studied LTSN0.25 ceramic exhibits excellent microwave dielectric properties, featuring a relative permittivity (u03B5r) of 18.6, ultra-high Qu00D7f of 102,330 GHz (at 7.76 GHz), and a near-zero TCF of u22122.3 ppm/u00B0C. Simultaneously, the stable THz response and simulated filter performance confirm its great potential for 5.5G applications.

This study investigates the influence of indium (In) addition on the properties of a near-eutectic Zn-3wt.%Al (Zn-3Al) alloy and the growth mechanism of intermetallic compounds (IMCs) at its interface with a Cu substrate. Zn-3Al-xIn (x = 0, 1.0, 3.0, 5.0 wt%) alloys with varying In contents were prepared via casting. The microstructure, thermal properties, wettability, and interfacial IMC growth behavior with the Cu substrate were characterized. Results indicate that In addition leads to the formation of two precipitate phases: an In-rich phase and a alpha-Al phase-at the grain boundaries of the matrix. The In-rich phase primarily precipitates adjacent to the alpha-Al phase. Concurrently, In addition lowers the alloy's melting point. At 3 wt% In, the precipitate phases exhibit a relatively uniform distribution and refined size, and the solder alloy demonstrates optimal wettability. In addition also induces the precipitation of In-rich phases at the solder/Cu substrate interface. These phases obstruct Zn/Cu interdiffusion pathways, thereby increasing the diffusion activation energy (Q). Furthermore, through a pinning effect, the In-rich phases suppress elemental diffusion and reduce the migration rate constant (k0), inhibiting interfacial IMC growth. However, excessive In addition (5 wt%) causes coarsening of the precipitate phases. This coarsening diminishes the pinning density and reduces Q, weakening the inhibitory effect. Consequently, In addition effectively enhances the wettability of the Zn-3Al solder alloy, suppresses interfacial IMC growth, and improves solder joint reliability, with optimal performance achieved at 3 wt% In.

In this work, an anion-engineering strategy was developed by substituting O2− with F− in Li2TiO3 ceramics. F− incorporation promoted liquid-phase-assisted densification, reduced the sintering temperature, and enhanced the Q×f value. Meanwhile, F− substitution induced a structural evolution from an ordered monoclinic phase to a disordered cubic phase, leading to the formation of a monoclinic–cubic dual-phase structure. The coexistence of these phases enabled compensation between positive and negative temperature coefficient of resonant frequency (TCF) contributions, resulting in excellent temperature stability. Furthermore, F− substitution provided multidimensional TCF regulation through both phase-fraction control and sintering-temperature adjustment. The Li2TiO2.9F0.2 ceramic sintered at 1050 °C exhibited the best overall balance between Q×f and TCF, with εr = 21.3, Q×f = 67,210 GHz, and TCF = −2.7 ppm/°C. These findings demonstrate an effective route for tailoring phase structure and microwave dielectric properties through anion substitution.

To develop efficient and fully water-splitting electrocatalysts, this study fabricated an amorphous/crystalline heterojunction, CoEr@ErFeP@CoMo 2 S 4 , on nickel foam using a hydrothermal-phosphorization method.

Cubic-phase lithium lanthanum titanate (Li0.33La0.56TiO3, LLTO) solid-state electrolyte exhibits a grain ionic conductivity of approximately 1.0 mS·cm⁻1 at room temperature. However, its high grain boundary resistance limits practical application. To further enhance the ionic conductivity, we employed an A/B-site co-doping strategy. Specifically, we introduced Sr2+ with a larger ionic radius into the A-site to widen the Li⁺ ion migration channels and Sb3+ into the B-site to promote cubic phase formation and stability. Co-doping with these two ions synergistically improves the electrolyte performance. The optimal sample, prepared with 0.02 mol of both Sr2+ and Sb3+ sintered at 1210 °C for 6 h, exhibits a total ionic conductivity of 7.77 × 10–2 mS·cm⁻1 and a grain density of 5.076 g.cm−3. Compared with the undoped LLTO electrolyte, the total ionic conductivity increases by approximately 20

Lightweight beta-Li2TiO3 ceramics are promising microwave dielectrics for the large-scale deployment of 5.5G extremely large antenna arrays (ELAAs). However, their practical application is hindered by the limited Q & times;f value (where quality factor Q = 1/dielectric loss (tan delta), and f represents the resonant frequency) and large positive temperature coefficient of resonant frequency (TCF), while the underlying phase transition and regulatory mechanisms remain elusive. Here, a unique monoclinic-cubic dual-phase architecture is constructed in Li2Ti1-x (Sc1/2Nb1/2) x O3 (LTSN x , 0 <= x <= 0.5) ceramics. In situ structural characterizations reveal that the substitution-induced reduction in the phase transition temperature (T c) and concomitant lattice distortion synergistically impede the reversed-phase transformation, stabilizing the high-temperature cubic phase at room temperature. Consequently, the inherent negative TCF of the cubic phase effectively compensates for the positive value of the monoclinic matrix, achieving exceptional temperature stability. Furthermore, the reconstructed superlattices and suppression of lattice defects significantly minimize dielectric loss. Of particular importance is that the studied LTSN0.25 ceramic exhibits excellent microwave dielectric properties, featuring a relative permittivity (epsilon r) of 18.6, ultra-high Q & times;f of 102,330 GHz (at 7.76 GHz), and a near-zero TCF of -2.3 ppm/degrees C. Simultaneously, the stable THz response and simulated filter performance confirm its great potential for 5.5G applications.

Li2-2xNixTiO3 ceramics were synthesized via a solid-state method, and the effects of Ni2+ substitution on the crystal structure, microstructure, and dielectric properties were systematically investigated. Structural analyses revealed that all compositions predominantly retained the monoclinic rock-salt structure, suggesting a high tolerance to Ni incorporation. Furthermore, Ni2+ substitution at the Li site effectively suppressed cleavage-induced microcracks by strengthening the local bonding and disrupting the continuity of the weak Li-O layers. Coupled with the elimination of surface pores, this optimized microstructure led to an enhanced quality factor (Q×f value) of 49,690GHz at x = 0.2. Moreover, Ni2+ substitution enabled continuous tuning of the temperature coefficient of resonant frequency (TCF) from +15.3 to −22.3 ppm/°C. Ultimately, the x = 0.25 ceramics sintered at 1200 °C exhibited the optimal comprehensive microwave dielectric properties (εr = 20.1, Q×f = 49,580GHz, TCF = +9.2 ppm/°C). This work confirms the feasibility of tuning the microwave dielectric properties of Li2TiO3 ceramics via Li-site substitution.

This work overcomes the long-standing brittleness and poor machinability of B4C by in-situ introduced conductive ScB2C2 network via reactive hot-pressing. The optimized composite containing 20 vol% ScB2C2 (BS-20) achieves a record fracture toughness of similar to 10.5 MPam(1/2)-over twice that of monolithic B4C-enabled by residual stress fields from thermal-expansion mismatch and atomically coherent interfaces that promote crack deflection and bridging. Simultaneously, the percolating ScB2C2 network enables a semiconductor-to-conductor transition (similar to 0.65 x 10(3) S/m), thereby unlocking electro-discharge machining of complex geometries, a critical advance for practical deployment. Furthermore, the BS-20 composite demonstrated exceptional laser ablation resistance, sustaining high power densities (up to similar to 1.6 x 10(7) W/cm(2)) without catastrophic failure, due to enhanced mechanical properties, energy dissipation and protective oxide scale formation. This work introduces a new class of damage-tolerant, electro-machinable, and laser-resistant B4C-based composites, establishing a generalizable strategy for designing multifunctional ceramics capable of reliable performance in extreme environments spanning aerospace, defense, and precision engineering.

Li-conducting oxide material Li7La3Zr2O12 solid state electrolytes have been considered as candidates to replace lithium batteries with organic liquid electrolytes due to their relatively high conductivity. This work offers the first systematic study on the electrochemical performance of single-site Gd doped LLZO from synthesis to characterization, where Gd3+ exclusively substituted for La3+. The varying Gd3+ concentration effect (Li7La3-xGdxZr2O12) on phase formation, microstructure, and ionic transport were systematically elucidated. Analysis reveals that isovalent Gd3+ substitution induces a localized contraction of the LaO8 dodecahedra. This steric effect optimizes the size of the lithium-ion migration bottlenecks and orders the lithium sublattice, which collectively lowers the activation energy for ionic hopping. Notably, this novel doping approach not only effectively stabilizes the cubic garnet phase but also yields a remarkably 4.48 & times; 10-4S center dot cm-1 total ionic conductivity of at RT. This performance rivals and in some cases surpasses that of many established doped systems. Our findings challenge the prevailing paradigm that exceptionally high conductivity in LLZO necessitates aliovalent doping or complex co-doping schemes. Instead, an established isolvalent single-site Gd3+ doping at the La site as a potent, previously overlooked strategy that provides new fundamental insights into ionic conduction mechanisms and presents a promising direction for developing advanced solid-state electrolytes.

The durability of hypersonic structures is limited by catastrophic oxidation of conventional ultra-high temperature ceramics. Here, we investigate the oxidation of a novel high-entropy carbide, (5RE1/5)Al3C3, between 900 and 1300 degrees C, and reveal a multi-stage protection-failure mechanism that outperforms benchmark carbides. Oxidation begins with a transient amorphous RE-Al-C-O layer, which crystallizes into an ultra-dense nano-crystalline (5RE1/5)3Al5O12/Al2O3 scale, forming a robust diffusion barrier. Exceptional stability arises from a dual high-entropy effect: high configurational entropy in both the carbide and its oxide suppresses cation diffusion and arrests grain growth, maintaining protection up to 1200 degrees C. Even at 1300 degrees C, a dual-layer scale persists, with eventual linear-kinetic degradation governed by localized destabilization of the amorphous interlayer leading to microporosity, not catastrophic cracking. This work provides the first mechanistic evidence for dual high-entropy protection, establishing a new design principle for oxidation-resistant ceramics.

The blue-green 3 YSZ ceramic doped with a single luminescent ion poor thermal stability at elevated temperatures and suffers from low color saturation. Moreover, simultaneously optimizing both color rendering and photoluminescence quantum efficiency remains a significant challenge. In this study, a vivid blue-green 3 YSZ ceramic exhibiting photoluminescence was synthesized via the solid-state reaction method through controlled co-doping with Ni2+ and Al3+ ions. The investigation into the coloration mechanism reveals that a portion of the Ni2+ ions substitutes for Zr4+ sites within the 3 YSZ crystal structure, while the remaining Ni2+ ions, together with Al3+ ions, participate in the formation of NiAl2O4 spinel phase. The outermost electrons of Ni2+ in the octahedral crystal field selectively absorb specific wavelengths of visible light and reflect green light, thereby contributing to the observed coloration. The luminescence property analysis indicates that the sample doped with 0.25 wt% NiO and 1.0 wt% Al2O3 exhibits the highest emission intensity, with a fluorescence lifetime of 0.203 mu s The emission peak observed at 505 nm is assigned to the d-d electronic transition of Ni2+ ions in an octahedral crystal field environment. Furthermore, the ceramic retains more than 51% of its initial luminescence intensity at 450 K, corresponding to a thermal activation energy (Delta E) of 0.09239 eV, demonstrating excellent thermal stability of the material.

Na3+xZr2Si2+xP1-xO12(x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) solid-state electrolytes were synthesized via a solid-state reaction method by modulating the Si/P ratio. The influence of the Si/P ratio on the crystalline structure and ionic transport properties was comprehensively investigated. The results demonstrate that increasing the Si/P ratio not only effectively facilitates the phase transition from a monoclinic to a highly conductive rhombohedral structure but also promotes grain growth. This grain enlargement reduces structural defects, such as grain boundaries and pores, thereby significantly diminishing grain boundary resistance. Furthermore, the partial aliovalent substitution of P5+ by Si4+ expands the unit cell volume and broadens the ion transport bottleneck size within the crystal lattice. This substitution further increases the concentration of Na+ charge carriers, leading to an enhanced intrinsic ionic conductivity. Concurrently, the elevated Si/P ratio effectively increases the oxygen vacancy concentration, contributing to the overall improvement in total ionic conductivity. Consequently, the optimized composition (Si/P = 2.4/0.6) achieves a peak room-temperature total ionic conductivity of 3.4 mS/cm with a low activation energy (Ea) of 0.146 eV, representing a 340% enhancement relative to the pristine sample.

A series of Cu-ScB2C2 composites with 0, 5, 10, 15, and 20 vol% ScB2C2 were synthesized via hot-pressing at 930 degrees C. The microstructures, phase compositions, electrical conductivity, tensile properties, and tribological behaviors of the composites were systematically investigated. TEM analysis, assisted by FIB preparation, confirmed the absence of interfacial reactions or elemental diffusion between the copper matrix and ScB2C2 particles. Electrical conductivity of the composites decreased progressively with increasing reinforcement content, ranging from 81 +/- 4% IACS for the Cu-5 vol% ScB2C2 composite to 62 +/- 2% IACS for the Cu-20 vol% ScB2C2 composite. Among all investigated composites, the Cu-5 vol% ScB2C2 sample exhibited the highest ultimate tensile strength, the greatest elongation, and the most favorable wear resistance, both in air and in 3.5 wt % NaCl solution.

Modern wireless communication systems put higher requirements on microwave dielectric ceramics in terms of dielectric properties, temperature stability, and low-temperature sintering process. To address the challenges associated with high-frequency signal attenuation, thermal effects, and the high-density integration of multiple-input multiple-output systems, microwave dielectric materials based on the Li2Ti1-x(Fe1/2Nb1/2)xO3 ceramic system were designed and prepared in this study. A monoclinic (cation-ordered)-cubic (cation-disordered) biphasic composite structure was engineered via (Fe1/2Nb1/2)4+ solid solution-induced phase transition, enabling effective tuning toward a near-zero temperature coefficient of resonance frequency (TCF). When x = 0.05, the composite ion synergistic effect significantly suppresses the oxygen vacancy defects and achieves an optimal Q × f value of 65,320 GHz. Furthermore, different proportions of LiF (in the range of 0-8 wt %) were investigated, and the introduction of 4 wt % LiF effectively reduces the sintering temperature of the ceramic to 925 °C, meeting the requirements of the low-temperature cofired ceramic process. The optimized ceramic exhibits excellent dielectric properties (εr = 22.3, Q × f = 70,300 GHz (at 7.32 GHz), TCF = -6.1 ppm/°C) and strong compatibility with silver electrodes. A prototype microstrip patch antenna designed using this ceramic for the BeiDou B1C band (operating at 1.575 GHz) demonstrated high simulated radiation efficiency (96.1%) and gain (4.0 dBi). This study represents significant advancements in TCF precision tuning and low-temperature sintering, offering innovative material solutions for 5G/6G communication devices.

The need for all-solid-state batteries with superior energy density has intensified interest in Li7La3Zr2O12 garnet-type solid electrolytes. While Ta doping has proven effective for cubic phase LLZO stabilization, further research is needed in optimizing doping amount and performance for practical applications. Conventional synthesis methods often require high dopant concentrations (x ≥ 0.4 in Li7−xLa3Zr2−xTaxO12) to achieve peak performance. This study demonstrates that a successful synthesis of LLZTxO, x = 0.0–0.40 mol ceramics resulted from a meticulously optimized solid-state synthesis protocol, featuring extended high-energy ball milling and precise sintering control, enabling superior electrochemical performance at a significantly reduced Ta doping level. Remarkably, this work outperformed many reports with higher Ta content, achieving 0.21 eV activation energy and 1.07 mS cm⁻¹ high ionic conductivity at an optimum composition of x = 0.20 mol at 30 °C. The critical current density (CCD) of the Li metal symmetric cell was measured at 1.4 mA·cm− 2. Structural (XRD, Rietveld refinement) and microstructural (SEM) analyses confirm the cubic phase stability and reveal highly dense, well-sintered morphology at this optimal doping level. This work contests the current view of high dopant addition by demonstrating that process optimization is a critical, often overlooked factor in maximizing dopant efficacy. It establishes an efficient, reproducible route for producing advanced solid-state batteries with high-performing garnet electrolytes.

This study aims to fabricate prestressed alumina ceramics exhibiting high strength and high toughness by applying a low-thermal-expansion kyanite coating to an alumina matrix substrate. Through a brush-coating process followed by pressureless sintering, prestressed alumina ceramics were successfully prepared utilizing in-situ kyanite decomposition to generate a mullite-based coating with controlled thermal expansion mismatch. By adjusting the kyanite content, the coefficient of thermal expansion (CTE) of the coating was precisely controlled to create a designed mismatch with the substrate, thereby introducing compressive prestress. The study systematically investigated the phase transformation, microstructural evolution, and crystallization kinetics of kyanite within the coating. Furthermore, the effects of the cross-sectional area ratio and the CTE difference between the coating and the matrix, as well as the influences of sintering conditions and ball-milling duration on the flexural strength of the ceramics, were studied in detail. The results demonstrated that at a temperature of 1350 degrees C, kyanite underwent extensive decomposition into granular mullite. Subsequent heating to 1500 degrees C induced secondary mullitization, resulting in the formation of short columnar mullite crystals. Under the optimized processing conditions (75% kyanite content, 30 h ball milling, and sintering at 1560 degrees C for 1 h), corresponding to a CTE difference of 3.67 & times; 10-6/degrees C between the coating and substrate and a cross-sectional area ratio of 35.43, the prestressed alumina ceramic was obtained.The composite achieved a flexural strength of 433.46 +/- 11.49 MPa, corresponding to a 42.54% increase over the substrate (304.10 +/- 27.74 MPa), while the fracture toughness reached 4.04 MPa m1/2, representing a 13.48% enhancement compared with the unreinforced sample (3.56 MPa m1/2). Furthermore, the critical temperature at which the residual strength begins to decline was elevated from 220 degrees C to 260 degrees C in the prestressed ceramic, in comparison to the uncoated substrate.