Developing environmental barrier coating (EBC) materials with superior calcium–magnesium–aluminosilicate (CMAS) corrosion resistance represents a current research priority in rare-earth (RE) silicates. Previous studies have demonstrated that a multicomponent rare-earth design can significantly enhance CMAS resistance, driven by the distinct behaviors of rare-earth elements during the corrosion process. This study investigates the synergistic mechanisms of the RE element in disilicates. We designed three multicomponent (RE1/4Tm1/4Yb1/4Lu1/4)2Si2O7 (RE = Gd, Ho, and Sc) materials and subjected them to CMAS corrosion at 1300 °C for durations of 1, 4, and 50 h to elucidate the synergistic mechanisms of multicomponent rare-earth elements on CMAS corrosion. We systematically analyzed the role of rare-earth cations in CMAS corrosion by examining their influence on the evolution of reactants and products. The results reveal that performance divergence in corrosion primarily stems from a mechanistic transition from dissolution–reprecipitation to intergranular penetration, governed by rare-earth ionic characteristics (mainly the cation radius). Comparative analysis confirms that an optimal active/inert stoichiometric ratio could simultaneously promote precipitation-induced corrosion mitigation and intrinsic resistance enhancement, establishing a design framework for multicomponent rare-earth disilicates in anti-CMAS EBC applications.
Abstract Heat accumulation and severe light scattering limit the applications of near-infrared phosphor-converted LEDs (NIR pc-LEDs) in the high-power field. Replacing phosphor encapsulation with Cr3+-doped glass-ceramics (GCs) provides an effective solution. However, obtaining transparent GCs with high thermal quenching resistance remains challenging. In this work, a novel Cr3+-doped MgNb2O6 GC was fabricated by co-melting and controlled crystallization using glass-forming and target-phase precursors. The resultant GCs possess acceptable transmittance and favorable thermal quenching resistance. By tuning the Mg/Nb ratio, a single MgNb2O6 crystalline phase was precipitated, and a two-step heat treatment optimized the GC transmittance. With nucleation temperature rising from 670 ℃ to 750 ℃ and crystallization temperature increasing from 820 ℃ to 960 ℃, crystallinity, grain size and luminous intensity gradually increase, whereas transmittance decreases monotonically. Cr3+ are proposed to simultaneously occupy Mg2+ and Nb5+ sites in MgNb2O6. Broadband NIR emission covering 600–1300 nm with a full width at half maximum (FWHM) of 210 nm is achieved, arising from intermediate and weak crystal fields and moderate electron-phonon coupling. After nucleation at 730 ℃ and crystallization at 940 ℃, the optimized GC shows a transmittance of approximately 50% and a high absorptivity of 60.5%. The GC exhibits favorable thermal quenching resistance, retaining 67.5% initial luminous intensity at 373 K. The NIR LED device integrated with the MgNb2O6:Cr3+ GC delivers an output power of 240.9 mW and a power conversion efficiency of 6.3%, demonstrating promising application prospects in night-vision illumination, food testing, biomedical and anti-counterfeiting fields.
Abstract Ultrasonic transducers have long relied on lead-based piezoelectric materials. However, the potential harm of lead to the environment and human health has spurred an urgent demand for environmentally friendly lead-free alternative materials. Bismuth sodium titanate (BNT) is regarded as a promising piezoelectric material for lead-free transducers due to its low dielectric constant and acoustic impedance. To address the problem that the previously developed 0.84BNT-0.133BKT-0.027BT composition still struggles to meet the requirements of high-quality biological tissue imaging, this study adopted an acceptor doping strategy and prepared a B-site Fe3+-doped lead-free piezoceramic system. The results show that appropriate Fe3+ doping produces a favorable balance between R3c/P4bm phase-structure modification and defect-related pinning, thereby enhancing the electromechanical response. At x = 0.01, the piezoelectric coefficient reaches the maximum value of 180 pC/N, while kt reaches 0.42, indicating enhanced thickness-mode electromechanical coupling. The planar 10 MHz ultrasonic transducer fabricated with this composition exhibits high sensitivity, with an insertion loss |IL| of 16 dB. After introducing an acoustic focusing lens, the focused transducer achieves axial and lateral resolutions of 182 and 264 μm, respectively. In addition, clear imaging of the internal structure of a porcine eyeball and the surface of a commemorative coin was successfully achieved. These results confirm that the B-site Fe3+-doped modified BNT-BKT-BT ternary lead-free ceramic has great application potential in high-performance environmentally friendly medical ultrasonic transducers.
Abstract Pb-based ferroelectric ceramics face a fundamental trade-off between high piezoelectric response (d33) and low Curie temperature (Tc). Here, we demonstrate that combining Sm-doping with a high-Tc PbHfO3 (PH)-based ternary matrix can effectively shift this balance. A series of 0.01Sm-0.2PMN-(0.8−x)PH-xPT ceramics were designed and systematically characterized. A morphotropic phase boundary (MPB) was identified at x ≈ 0.435, where the optimized composition exhibits a high d33 (≈ 830 pC/N) together with an elevated Tc (≈ 256 °C), a combination that lies above the typical d33–Tc trend of Pb-based ferroelectric ceramics. In addition, the ceramic exhibits stable piezoelectric performance up to ~230 °C, indicating excellent thermal stability. A full-matrix electromechanical characterization was performed, yielding a self‑consistent set of elastic, dielectric constants, and piezoelectric coefficients. Compared with a commercial PZT 610HD benchmark, the designed ceramic offers a comparable d33 but a 70 °C higher depolarization temperature. Atomic-resolution TEM reveals heterogeneous local polar configurations in the optimized composition, providing microscopic structural evidence consistent with its excellent piezoelectric performance. This comprehensive property set not only clarifies the intrinsic structure–property relations but also provides a reliable database for high‑temperature piezoelectric device design.
Abstract Ceramics are valued for their high strength, thermal stability, and chemical inertness, but their structural applications are limited by intrinsic room-temperature (RT) brittleness. The stress required for dislocation motion in strongly ionic/covalent ceramics often exceeds their fracture strength, leading to catastrophic failure before plastic deformation occurs. Overcoming this limitation remains a major challenge in materials science. Recent studies have shown that ceramics exhibit RT plasticity through mechanisms including dislocation, phase transformation, and grain boundary sliding (GBS). These findings challenge the conventional view of ceramics as purely brittle materials and suggest that plasticity can be achieved not only in microscale specimens but also in bulk and structurally engineered ceramic systems. Several strategies have been developed to promote RT plasticity. Defect engineering, the controlled introduction and activation of dislocations, is critical for regulating deformation behavior. Structural designs such as coherent interfaces, layered architectures, and amorphous–crystalline composites can reduce dislocation nucleation barriers and improve deformation compatibility. Nanocrystalline structuring and external field regulation further enhance plasticity by altering local stress distributions and diffusion pathways. In situ characterization and strain measurement techniques have enabled direct observation and accurate quantification of deformation processes, improving the understanding of the relationship between structure, defects, and mechanical response. Despite these advances, achieving reliable and scalable plasticity in bulk ceramics remains challenging. Future work should focus on intrinsic plastic ceramic systems, scalable fabrication, and integrated multiscale design strategies. These efforts may enable the development of ceramics with improved damage tolerance and deformability for advanced structural and functional applications.
Hot oscillatory pressing (HOP) is an advanced sintering technique for producing ceramics with high mechanical performance; however, the underlying mechanism by which oscillatory pressure promotes densification and microstructural refinement remains inadequately understood. In this study, hysteresis analysis, adapted from metal fatigue models, was first applied to monitor the sintering behavior of Al2O3/TiCp composites in real time. Densification curves and hysteresis loops indicate that grain boundaries exhibit viscoelastic characteristics when grain boundary sliding dominates, and the oscillatory pressure optimizes sintering through cyclic softening and hardening. Initially, a softening process promotes grain boundary sliding to accelerate densification. As the density increases, energy dissipation due to internal friction induces a transition to cyclic hardening, thereby enabling simultaneous microstructural refinement and property enhancement. Microstructural analysis further reveals that, compared to static pressure, oscillatory pressure reduces grain boundary energy, inhibits grain growth, and enhances densification. The HOP-sintered composite exhibits a Vickers hardness of 21.8u00B10.3 GPa and flexural strength of 795u00B129 MPa, improvements of ~10% and 21.4%, respectively, over hot pressing (HP). This work establishes a mechanistic framework linking oscillatory pressure to microstructural evolution, providing theoretical support for the further development of HOP technology.
Polymer-derived SiC-based ceramic fibrous membranes have attracted increasing attention as lightweight and thermally stable electromagnetic wave absorbers. However, simultaneously achieving strong attenuation capability and good impedance matching remains challenging due to the limited regulation of phase composition and dielectric behavior. In this work, multiphase SiC-based fibrous membranes were prepared by electrospinning combined with polycarbosilane (PCS)-derived ceramic conversion. The phase evolution, fiber morphology, dielectric response, and electromagnetic wave absorption performance were regulated by tuning the PCS content and pyrolysis temperatures. Advanced characterizations confirm the formation of a heterogeneous u03B2-SiC/SiOxCy/carbon multiphase structure with good flexibility, which provides abundant polarization centers, moderate conductive pathways, and multiple reflection sites, thereby enabling balanced impedance matching and dielectric loss. Consequently, the sample with a PCS content of 1.4 g pyrolyzed at 1400 u00B0C achieves a minimum reflection loss (RLmin) of u221227.12 dB at a matching thickness of 2.2 mm and a maximum effective absorption bandwidth (EAB) of 8.22 GHz at 2.7 mm, covering 9.78u201318 GHz. Radar cross-section (RCS) simulation further verifies the electromagnetic scattering suppression capability of the optimized fibrous ceramic coating. Therefore, this study provides a useful strategy for tailoring the phase composition and dielectric behavior in polymer-derived SiC-based fibrous membranes for broadband electromagnetic wave absorption.
The Aurivillius-phase layered material SrBi2Ta2O9 possesses an extremely low leakage current (~10u22129 Au00B7cmu22122) along the out-of-plane direction with in-plane ferroelectricity, which brings difficulties in achieving high ferroelectric performance and low leakage current simultaneously in randomly oriented ceramics. Here, highly textured SrBi2Ta2O9 ceramics with a texture degree of f = 0.985 are prepared using templated grain growth (TGG) technology with a tape-casting method. The in-plane remnant polarization achieves 15.83 u03BCCu00B7cmu22122, which is increased by 197% compared with that of the SrBi2Ta2O9 randomly oriented ceramic. Doping Ca is found to reduce the in-plane leakage current density to J = 5.924u00D710u22127 Au00B7cmu22122, which is attributed to the increased electronic band gap. This research presents an effective route for developing high-performance SrBi2Ta2O9-based ferroelectric devices.
Hydrogen embrittlement is a serious issue faced by structural metal materials in hydrogen infrastructures. The development of protective coatings as efficient hydrogen permeation barriers is urgently needed. Here, we report a new nanocrystalline CeO2 coating with a thickness of ~40 nm successfully fabricated via the coordination-assisted deposition method. By optimizing the annealing conditions, the resultant CeO2 coating has a uniform and dense structure, albeit with a high density of dislocations and grain boundaries. Its hydrogen permeation barrier performance was evaluated by a gas-driven deuterium permeation test, achieving an ultralow permeability of 1.64u00D710u221215 molu00B7su22121u00B7mu22121u00B7Pau22121/2 at 500 u00B0C, which is three orders of magnitude lower than that of stainless steel. The corresponding hydrogen permeation reduction factor (PRF) reaches an ultrahigh value of 2355, which is 4u201375 times that of the other oxide nanocoatings, such as ZrO2, Al2O3, Cr2O3, and Er2O3. The intrinsic hydrogen diffusion mechanism in the single-crystal coating is revealed by first-principles calculations. In the polycrystal coating, the dense dislocation and boundary-containing nanocrystalline structure not only provides abundant hydrogen traps but also prolongs the diffusion pathway to effectively impede hydrogen permeation. This study demonstrates the great potential of CeO2 as a new type of hydrogen-resistant material and, most importantly, the roles of microstructure in the design of ultrathin hydrogen permeation barriers with high performance.
The ever-growing global energy demand has driven a surge of research interest in the field of energy harvesting and conversion. Among them, high-power force-electric energy conversion devices based on charge storage via the polarization effect of ferroelectric (FE) materials have attracted considerable interest for specialized applications owing to their advantages of long shelf life, ultrafast response, and high current/voltage output. Nevertheless, the primary bottleneck hindering the development and practical deployment of such energy storage systems lies in the low remanent polarization (Pr) and insufficient thermal stability of most state-of-the-art lead-free ferroelectric materials. In this work, a synergistic optimization strategy of composition-driven structural distortions and defect-induced pinning effects via silver niobate (AN) and MnCO3 doping is applied to bismuth sodium titanate (BNT)-based ferroelectric ceramics. The optimized 0.98Bi0.5Na0.5TiO3u20130.02AgNbO3u20130.20 wt% MnCO3 lead-free ferroelectric ceramics exhibit significantly enhanced Pr and thermal stability, achieving an ultrahigh Pr of 52.21 u03BCC/cm2 and excellent stability up to 160 u00B0C. The practical benefits of this synergistic strategy are exhibited in force-electric energy conversion applications. The multilayer ceramic capacitors (MLCC-BNT) deliver a record-breaking peak pulse current of 90 A via a pressure-induced phase transition from the ferroelectric R3c phase to the nonpolar Pnma phase. The proposed strategy provides a highly feasible approach for enhancing the ferroelectricity and thermal stability of lead-free ferroelectric materials, thereby establishing a solid material foundation for high-power force-electric energy conversion.
The convergence of optics and electronics, driven by intelligent systems and wearable technologies, demands materials that seamlessly integrate optical transparency with robust electrical and mechanical functionalities. Transparent ferroelectric ceramics (TFCs) have emerged as a pivotal platform in this endeavor, uniquely bridging high optical transmittance with strong ferroelectric, piezoelectric, and electro-optic (EO) responses. This review comprehensively charts the evolution of TFCs, from fundamental material design to cutting-edge device applications. We systematically analyze the core strategies for achieving transparency in two representative transparent ferroelectric ceramic systems, namely, lead-based (Pb(Mg1/3Nb2/3)O3u2013PbTiO3, abbreviated as PMN-PT) and lead-free ((K,Na)NbO3, abbreviated as KNN) systems, while also discussing other important systems, such as (Pb,La)(Zr,Ti)O3 (PLZT), BaTiO3 (BTO), and (Bi0.5Na0.5)TiO3 (BNT), where appropriate for comparison. Critical mechanisms include grain and domain engineering, refractive-index matching, phase-structure tuning, and defect control. Representative functionalitiesu2014including transparent piezoelectricity, EO modulation, energy storage, photoluminescence, and photochromismu2014are highlighted, with their potential applications evaluated across photoacoustic imaging (PAI), adaptive optics, transparent robotics, smart windows, and optical communication. Finally, we identify key challenges and future opportunities, such as high Curie temperature (Tc) design, texture engineering, and multifunctional co-integration. Overall, this review aims to provide theoretical insights and material-design foundations for next-generation multifunctional transparent ferroelectric devices, accelerating their adoption in intelligent sensing, integrated photonics, and transparent optoelectronic systems.
Advanced temperature-sensitive materials play an increasingly important role in modern hypersonic propulsion technology. For such applications, ensuring long-term high-temperature (above 1000 u00B0C) stability is key to enabling integrated structural and functional capabilities. Herein, we develop a Mo-regulated high-entropy ferroelastic niobate strategy for ultrawide-temperature negative-temperature-coefficient thermosensitive ceramics. Density functional theory (DFT) calculations show that the A-site high-entropy facilitates Mo doping in (Ca0.2La0.2Ce0.2Eu0.2Gd0.2)NbO4. Consequently, Mo doping broadens the distribution of local atomic configurations, modulates ferroelastic domain structures, and increases atomic-scale displacement disorder. These structural changes redistribute Hall transport contributions and reduce the mismatch between grain and grain-boundary transport barriers. As a result, the developed ceramics exhibit highly linear Arrhenius behavior (R2 = 0.99907) over an ultrawide temperature range from u221250 to 1250 u00B0C, accompanied by a low B-value fluctuation of only 4.44%. High-temperature impedance analysis further confirms closely matched grain and grain-boundary activation energies, with a minimum activation-energy mismatch ( u0394Ea) of only 0.009 eV. During aging at 1250 u00B0C, the ceramics exhibit aging-induced postdensification accompanied by an increase in relative density and strain redistribution, resulting in excellent long-term stability with a stabilized-stage resistance drift as low as 1.09% after 1000 h. These findings demonstrate that manipulating entropy-stabilized defects provides a robust pathway to decouple sensitivity from degradation in functional ceramics under thermal stress.
The difficult synthesis and low purity of 413 high-entropy MAX phase powders have severely constrained their development in the field of electromagnetic wave absorption. To address this, the present study optimized a two-step solid-phase synthesis process. By examining how different raw-material pretreatment methods affect the structural evolution of carbide precursors, we proposed a u201Cstructural genetic mechanismu201D that systematically explains the synthesis pathway of the 413 high-entropy MAX phase. The results show that cubic-phase carbide precursors are essential for producing 413 high-purity high-entropy MAX. Using the optimized method, we synthesized pure-phase 413 high-entropy MAX and, for the first time, successfully prepared (Mo0.2Ta0.2Nb0.2Ti0.2V0.2)4AlC3 via a conventional pressureless solid-state reaction route. Wave absorption tests indicate that the synthesized 413 high-entropy MAX phases all exhibit good absorption performance. In particular, (Mo0.2Cr0.2Nb0.2Ti0.2V0.2)4AlC3 achieved a maximum effective absorption bandwidth (EABmax) of 4.24 GHz at a thickness of 1.57 mm and a minimum reflection loss (RLmin) of u221252.88 dB at 1.87 mm. (Mo0.2Ta0.2Nb0.2Ti0.2V0.2)4AlC3 showed a clear advantage at small thicknesses, with an EABmax of 3.44 GHz at 0.93 mm and an RLmin of u221251.60 dB at 0.89 mm. This study fully demonstrated the effective regulation of wave absorption performance by high-entropy engineering and provided an effective approach to expand the types of 413 high-entropy MAX phase powders, offering a useful reference for exploring this material in the field of wave absorption.
Abstract High-entropy engineering has emerged as an effective strategy for tailoring structural disorder and functional responses in tetragonal tungsten bronze (TTB) ferroelectrics. However, how configurational entropy, crystal structure, modulation characteristics, and relaxor dynamics govern the macroscopic electrical response remains insufficiently understood. Here, K(NaPr)1-x(SrBa)xNb5O15 ceramics with continuously varying configurational entropy were designed to investigate the origin of relaxor-ferroelectric evolution. With increasing Sr/Ba substitution, the electrical response evolves from an ergodic-relaxor state with slim hysteresis loops and four current peaks to a ferroelectric-like state with double current peaks, fatter loops, and increased remanent and maximum polarizations. This evolution is accompanied by increased lattice parameter c and tetragonality (c/a), indicating a structural evolution toward a more stable polar state. The dielectric anomalies and Vogel-Fulcher analysis further reveal an increase in freezing temperature and a decrease in activation energy, indicating strengthened coupling among polar nanoregions and a gradual evolution from the relaxor state toward a non-ergodic relaxor or ferroelectric state. Notably, this trend is opposite to the commonly expected enhancement of relaxor behavior in high-entropy systems, suggesting that configurational entropy does not simply strengthen relaxor characteristics through increased compositional disorder. Instead, configurational entropy modulates the order-disorder state of A-site occupation, thereby changing the octahedral tilting patterns and the modulation structure, which affects the diffuseness of the phase transition. These results demonstrate that the macroscopic electrical response in the high-entropy K(NaPr)1-x(SrBa)xNb5O15 system is regulated by crystal structure, modulation structure, and polar nanoregion dynamics, providing new insight into the relaxor behavior of TTB ferroelectrics.
Abstract The engineering application of transition metal carbides is often constrained by the inherent hardness-toughness trade-off. While phase modulation is an effective strategy, the intrinsic brittleness of ceramics still limits the achievable toughening. Taking (Ti, Zr, V, Nb, Mo)C high-entropy carbide as a model system, this work proposes a novel strategy to reconcile this trade-off by leveraging synergistic phase separation and precipitation. The as-sintered single-phase solid solution was subjected to optimized aging treatment, yielding a microstructure characterized by coexisting spinodal decomposition domains and precipitates. Specifically, a multi-scale synergistic strengthening mechanism is revealed. At the atomic scale, unique interface engineering combines semi-coherent spinodal interfaces with incoherent precipitate interfaces. This activates micro-scale defect engineering by inducing high-density dislocations, nano-twins, and stacking faults. This multi-scale system constructs a composite structure at the meso-scale where spinodal and precipitation domains coexist, effectively impeding dislocation motion and deflecting crack propagation. Driven by this mechanism, the material aged at 1300 °C for 20 h achieves an optimal synergy of properties, demonstrating concurrent increases in hardness (36%) and fracture toughness (45%) compared with the as-sintered state. This work opens a new avenue for designing advanced ceramic materials with superior damage tolerance.
Abstract Dielectric capacitors have been recognized as promising devices for advanced pulse power systems due to their high-power density and fast charge-discharge rates. The dielectrics must simultaneously achieve large energy storage density and high efficiency to support the rapid development of dielectric capacitors. Among the various dielectric ceramics investigated so far, the Bi0.5Na0.5TiO3 (BNT)-based lead-free relaxor ferroelectric has recently become increasingly attractive for dielectric energy storage owing to its high spontaneous polarization and temperature corresponding to the peak of maximum permittivity (Tm) in dielectric constant spectroscopy. Extensive efforts have been devoted to developing high-performance BNT-based ceramics in extreme conditions, and significant progress has been made. To meet the application demands of energy storage devices across diverse electric fields, it is imperative to understand the fundamental principles of energy storage and devise targeted optimization strategies for BNT-based ceramics. This review provides an overview of energy storage theory and essential determinants governing capacitive performance of dielectric materials, encompassing polarization response, breakdown characteristics, relaxation behavior, and dielectric properties. Furthermore, we elucidate tailored multiscale design strategies to optimize the energy storage capability of BNT-based ceramics across various electric field (E-field) regions: low E-field (< 300 kV/cm), moderate E-field (300 - 500 kV/cm), and high E-field (˃ 500 kV/cm). We further present the developmental progress and future outlook of BNT-based ceramics for advanced electrostatic capacitor applications.
Introducing a surface compressive stress layer is an effective way to enhance the strength of brittle ceramics, yet achieving such prestressing intrinsically in monolithic oxide ceramics remains challenging. Here, we report a novel method called oxygen-vacancy compensation prestressing (OVCP) to generate in situ surface prestressing in zirconia-toughened alumina (ZTA) ceramics. Oxygen vacancy-rich ZTA was first produced by vacuum hot pressing, followed by air annealing to induce surface reoxygenation and form an oxygen-charged layer (OCL). The optimized treatment increased the flexural strength to (1679u00B178) MPa, representing a 31% improvement over the unannealed state. Oxygen-vacancy compensation during annealing induces lattice expansion in the near-surface region. Constrained by the less-oxidized interior, this lattice expansion is converted into a residual compressive stress field that suppresses bending-induced failure. A simplified bilayer model quantitatively supports the experimentally observed strengthening behavior. These findings establish oxygen vacancy-regulated lattice expansion as an effective mechanism for intrinsic surface prestressing and provide a simple, interface-free route for strengthening oxide ceramics.
The ultrahigh sintering temperatures required for high-entropy borides (HEBs) pose a significant challenge to their processing and practical application. This study introduces an efficient low-temperature fabrication route for dense HEB-based ceramics using reactive ZrSi2-assisted heavy direct current sintering, with a maximum heating rate exceeding 3700 u00B0C/min. A porosity of 1.60%u00B10.61% can be achieved at a sintering temperature of 1000 u00B0C, which is reduced by 600u20131000 u00B0C compared to state-of-the-art spark plasma sintering (SPS)/field-assisted sintering technique (FAST) processing of HEBs. Microstructural analysis revealed interdiffusion between HEB and ZrSi2, leading to a coreu2013shell HEB architecture and layered high-entropy silicides (HESs). Meanwhile, dislocations and nonuniform stress fields were observed within the HEB grains. These microstructural features synergistically inhibit crack propagation and promote crack deflection and branching. Consequently, both flexural strength and fracture toughness (KIC) are significantly enhanced. A flexural strength of 963u202FMPa was attained at 1400u202Fu00B0C, and a KIC of 7.4u202FMPau00B7m1/2 was achieved at 1500u202Fu00B0C, surpassing most reported HEB-based ceramics. These results demonstrate that reactive ZrSi2-assisted heavy direct current sintering is a profoundly effective approach for the low-temperature manufacturing of high-performance HEB-based ceramics.
The escalating complexity of the electromagnetic environment calls for advanced electromagnetic wave (EMW) absorption materials capable of efficient multi-frequency attenuation. Silicon carbide (SiC) is a promising dielectric candidate but is hindered by intrinsic impedance mismatch and limited polarization loss. Herein, we report a novel ternary heterostructure absorber consisting of SiC nanowires synergistically coupled with dual rare-earth silicides (Ce5Si4 and Pr5Si4) fabricated via a combined magnesiothermic and carbothermal reduction process using an MFI-type zeolite precursor. This unique architecture creates an intricate porous network featuring abundant multiple heterogeneous interfaces (SiC/Ce5Si4, SiC/Pr5Si4, and Ce5Si4/Pr5Si4). The simultaneous incorporation of Ce and Pr optimizes the complex permittivity for impedance matching and induces intense multi-interfacial polarization relaxation. Consequently, the designed composite achieves efficient and strong EMW absorption performance in the C-band (4.30 GHz), X-band (8.24 GHz), and Ku-band (16.51 GHz), demonstrating remarkable multi-frequency point absorption performance. Radar cross-section (RCS) simulations further demonstrate its significant stealth capability, highlighting the potential of dual rare-earth synergistic engineering. This work provides a pioneering strategy for designing high-performance, multi-frequency SiC-based absorbers through the construction of ternary rare-earth silicide heterostructures.
High-entropy ultrahigh temperature ceramics (UHTCs) have garnered significant attention for their outstanding designability and performance, yet existing strategies remain largely confined to cationic sublattice engineering, leaving the potential of anionic site manipulation unexplored. Herein, we extend the entropy-stabilization paradigm to the anion sublattice by designing a multianion Hf0.8Zr0.2B0.1C0.5N0.4 solid solution. The resulting Hf0.8Zr0.2B0.1C0.5N0.4–SiC ceramic achieves negative ablation rates (−0.049 and −0.287 μm·s−1) under 2600 °C plasma flame exposure, markedly outperforming Hf0.8Zr0.2C–SiC. This exceptional ablation-resistant performance originates from the synergistic effects enabled by multianion sublattice engineering. The incorporation of B–C–N intrinsically enhances fracture toughness, while in situ precipitation of hexagonal graphite during ablation extrinsically arrests cracks through interfacial shear, preventing catastrophic disintegration. Furthermore, the multianion matrix undergoes a sequential oxidation process, forming an HfZrBCNO interlayer that acts as an oxygen scavenger. Concurrently, h-BN precipitates at grain boundaries, serving as compliant diffusion barriers that impede oxygen ingress into SiC. This dual-layer protection mechanism suppresses the active oxidation of SiC (SiC + O2 → SiO + CO) and promotes the formation of a dense, scouring-resistant HfZrO2–SiO2 composite barrier. By demonstrating simultaneous microstructural toughening and mesoscale oxidation management, this work establishes multianion sublattice engineering as a transformative platform for designing next-generation thermal protection materials beyond the limits of conventional entropy-stabilized ceramics.
