Alumina ceramics are widely utilized as structural materials, yet their inherent brittleness and monofunctionality limit their application in high-stress scenarios. Strategic integration of two-dimensional graphene sheets, characterized by their excellent mechanical, thermal and electrical properties, into ceramic matrix can facilitate grain refinement through interface engineering, thereby achieving performance optimization. Conventional physical blending methods result in poor uniformity and integrity of 2D sheets, thereby impeding advancements in graphene-ceramic composites. Herein, a novel adsorption-precipitation self-assembly (APSA) method was proposed for the nondestructive integration of graphene oxide (GO) sheets with submicron Al₂O₃ particles. A homogeneous precursor is obtained by uniform deposition of Al³⁺ ions adsorbed on GO surface, followed by low-temperature rapid densification via spark plasma sintering (SPS). For the resultant composites, the incorporated graphene is aligned parallel to the alumina grains, facilitating grain refinement and significantly enhancing the mechanical properties through synergistic effect of various toughening mechanisms, including pull-out, crack extension and bridging. In comparison to monolithic alumina ceramics, the ceramic composites exhibit a 43% enhancement in flexural strength ((428±87) MPa) and a 34% improvement in fracture toughness ((4.40±0.13) MPa·m^1/2). Furthermore, the strength and toughness values also increase by 15% respectively, compared to specimens made from the conventional ball-milling mixing process, confirming the efficacy and advancement of such a manufacturing approach.

Periodontitis is a clinical challenge caused by bacterial overgrowth, resulting in irreversible damage to periodontal tissue. Antibacterial sonodynamic therapy (aSDT) has emerged as a promising alternative to conventional debridement due to its excellent biocompatibility and tissue penetration capability. However, this therapy cannot cure the periodontitis solely, needing more exploration to find an effectively improved treatment. Here, Fe doped Ti based metal-organic frameworks (Fe/Ti-MOFs) were prepared to explore the relationship between Fe doping and sonoresponsive efficiency. Incorporation of Fe enabled precise modulation of the band structure and crystallinity while maintaining the lattice architecture. Results showed that Fe/Ti-MOFs exhibited enhanced hydroxyl radical (•OH) generation under ultrasonic irradiation, effectively facilitating the eradication of bacterial pathogens. Notably, the sample with a Fe/Ti molar ratio of 0.025 : 1 exhibited exceptional performance. The sonocatalytic activity was collectively influenced by bandgap engineering, Fe doping concentration and crystallinity. Moreover, Fe/Ti-MOFs exhibited no cytotoxicity toward gingival fibroblasts and maintained excellent biocompatibility, without adverse effects on tissue repair. The ultrasound responsive Fe/Ti-MOFs material developed in this study offers potential for mitigating the adverse effects of antibiotics and providing novel insights and strategies for the application of aSDT in periodontitis treatment.

Volatile organic compounds (VOCs), particularly aromatic hydrocarbons such as toluene, pose significant threats to the environment and human health due to their high volatility and biological toxicity. Traditional metal- organic frameworks (MOFs) are primarily microporous, and their trade-off between adsorption capacity and molecular transport efficiency has driven development of more advanced material systems. In this work, graphene oxide (GO) doped metal-organic framework gels (MOGs) based on UiO-66 were developed, leveraging the synergistic modification effect of GO. The π-conjugated structure of GO enhanced π-π interactions with toluene molecules, while its abundant oxygen-containing functional groups facilitated competitive coordination with metal nodes, leading to exposure of additional Lewis acid sites and thereby enhancing metal-π interactions. Experimental results demonstrated that UG-1 with a mass ratio of GO to ZrCl₄ at 1 : 100 exhibited a breakthrough adsorption capacity of 77.4 mg/g in dynamic adsorption experiments and a saturated capacity of up to 1245.5 mg/g in static tests, outperforming both UiO66 MOF and UiO66 MOG materials. In conclusion, this study elucidates multiple regulatory mechanisms of GO incorporation in modulating pore structure and host-guest interactions, providing a new theoretical basis and practical guidance for designing efficient and recyclable VOC adsorbents.

With increasingly strict regulations on exhaust emissions, the higher requirements have been built for filtration of diesel particulate filter (DPF) because traditional DPF cannot meet the demand for precise filtration of nanoparticles in exhaust. In this study, a series of Co_0.8Fe_xCe_0.2-xCr₂O₄ spinel-type catalysts were loaded on aluminum borate whiskers by hexadecyl dimethyl ammonium bromide (CTAB)-assisted co-precipitation method. The unique hierarchical microstructure design of “whisker enhanced filter-bimetallic doping catalytic oxidation” achieves a combination of efficient filtration performance and low-temperature catalytic performance, enabling catalytic oxidation of carbon soot particles at lower temperatures. Fe and Ce co-doping produces significant synergistic effects, increasing concentrations of oxygen species (oxygen vacancies), Co³⁺ and Cr⁶⁺ on the catalyst surface and enhancing reaction activity. Temperature of carbon soot particles at 50% conversion (T₅₀=446 ℃) is significantly lower than that of the blank cordierite sample (T₅₀=567 ℃). Five cyclic stability tests show that the catalysts have good stability and CO₂ selectivity (86%-94%). In conclusion, this unique hierarchical microstructure exhibits a unity of efficient particle filtration and low temperature catalytic combustion performance, with potential application in the field of DPF.

Decomposition of ammonia for hydrogen production is a promising method, but still needs developing low-cost, highly active and selective catalysts which can operate at moderate temperatures. In this study, carbon nano-onions (CNOs), a byproduct of methane pyrolysis at 850 ℃, were used as a support for loading active metal cobalt (Co) via a uniform deposition-precipitation method. Additionally, magnesium oxide (MgO) was introduced as a promoter to prepare a high-performance ammonia decomposition catalyst. An investigation was conducted on the effects of acid washing and potassium (K) activation treatments on morphology of the CNOs support and catalyst performance with in-depth exploration of their influence mechanisms. Various characterization and chemical adsorption experiments confirmed a positive correlation between basicity strength of the catalyst and its ammonia decomposition performance. It was revealed that incorporation of CNOs significantly enhanced electronic conductivity of the catalyst and facilitated uniform dispersion of Co₂MgO₄ nanoparticles on the support. This uniform dispersion increased the exposure of basic active sites, thereby enhancing the catalyst's ability to adsorb ammonia molecules. The acid washing treatment introduced more oxygen-containing functional groups on the CNOs surface which acted as anchoring sites to form strong chemical bonds (coordination or ionic bonds) with Co²⁺ or Mg²⁺, thus stabilizing Co₂MgO₄ particles. These strong chemical bonds increased the reduction difficulty of the metal oxides, leading to an elevated reduction temperature. Catalytic performance tests demonstrated that the synergistic effect of CNOs, MgO, K, and Co significantly optimized structural characteristics, metal particle size and catalytic performance of the catalyst. Among a series of synthesized catalysts, Co₂Mg/K-CNO’ exhibited the best catalytic activity for ammonia decomposition, achieving a conversion rate of 99.6% at 550 ℃ and a space-time yield of 12000 mL·g_cat^-1·h^-1.

Indium selenide (InSe), a typical layered III-VI semiconductor, has attracted intense interest owing to its high electron mobility, tunable bandgap and exceptional plastic deformation capability, enabling it a promising candidate for next-generation electronic, optoelectronic and flexible devices. Recently, the controlled growth of intrinsic InSe crystals has been well developed, whereas doping InSe crystals with a third element remains relatively scarce. In this study, intrinsic InSe crystals were grown using the Bridgman method, and high-quality Bi-doped InSe crystals were then prepared through introducing Bi during the crystal synthesis stage. Optical microscopy and scanning electron microscopy observations indicate that the as-grown Bi-doped InSe crystals exhibit a smooth surface and excellent single-crystalline characteristic. Raman spectroscopy and X-ray diffraction analyses further demonstrate that, after Bi doping, their phase structure is consistent with former intrinsic crystals, exhibiting ε-InSe phase. Chemical etching experiments reveal that the doped Bi atoms can interact with dislocation cores within the crystal, effectively suppressing their motion and significantly reducing their dislocation density. Electrical measurements show that the Bi doping markedly increases carrier concentration and mobility of InSe crystal at high temperature, which is primarily attributed to the introduction of additional free carriers and suppression of carrier scattering resulting from the reduced dislocation density. Consequently, Bi-doped InSe crystal was successfully fabricated, and its superior performance compared to the intrinsic InSe was verified. This work provides theoretical insights and experimental guidance for optimizing properties of InSe crystals in application in future devices.

Since ferroelectric properties of Al_1-xSc_xN thin films were experimentally confirmed in 2019, wurtzite-structured ferroelectric materials have received worldwide attention. However, the strong dependence of their ferroelectric performance on deposition parameters still remains a significant challenge, limiting their reliable integration into practical device applications. This study aims to systematically investigate the influence of sputtering working pressure on microstructural evolution and resultant ferroelectric properties of Al_1-xSc_xN thin films. The primary goal is to identify the optimal pressure window that yields superior ferroelectric performance and to understand the underlying structure-property relationships. Al_0.71Sc_0.29N thin films were deposited on silicon substrates using reactive magnetron sputtering in a pure nitrogen atmosphere, and experienced the working pressure varied from 0.27 Pa to 1.33 Pa. The correlation between crystal structure, surface morphology, and ferroelectric properties of the thin film was analyzed. The results showed that the working pressure significantly affected crystallization quality of Al_0.71Sc_0.29N thin films, among which prepared under 0.52 Pa had the best crystallization quality and excellent ferroelectric properties. As the working pressure increased, the pyramid-like structures began to appear on surface of the film and gradually increased, while the static leakage current also gradually decreased. This work conclusively demonstrates that sputtering working pressure is one of the decisive factors in tuning microstructure and ferroelectricity of Al_1-xSc_xN films. The correlation between working pressure-induced morphological changes and leakage current suppression offers valuable insights for engineering high-performance wurtzite ferroelectric devices.

Silicon carbide (SiC) photoconductive semiconductor switches (PCSS) are optoelectronic devices that utilize ultrafast pulsed lasers to modulate semiconductor resistivity for switching operations. Transparent oxide conductive films, especially zinc oxide thin films, are considered as a potential alternative electrode materials to reduce the on-resistance due to their excellent optical transparency and electrical conductivity. However, zinc oxide thin films are prone to ablation damage under high-energy pulsed laser irradiation, leading to crack formation and significantly affecting the device’s lifespan. Additionally, uneven local electric field distribution in the electrodes poses challenges to the long-term stability of the device. In this study, boron-gallium co-doped zinc oxide (BGZO) thin films were prepared by magnetron sputtering, and effects of annealing temperature (300-600 ℃) on their structural and electrical properties were investigated. X-ray diffraction and Hall effect measurements revealed that these films annealed at 400 ℃ exhibited optimal crystallinity and electrical performance, achieving a visible-light transmittance of 93% and a resistivity as low as 1.40×10^-2 Ω·cm. After integrating the optimized BGZO films as transparent electrodes into SiC PCSS devices, these BGZO-based devices, under 532 nm wavelength and 170 mJ pulsed laser excitation, exhibited more stable operation than conventional Ni-based electrodes, with reduced filamentary current damage at the SiC-electrode interface and improved electric field uniformity at the electrode edges. This study provides an optimized fabrication strategy for high-performance transparent conductive films and confirms their advantages in PCSS applications.

Hard carbon is a promising anode material for sodium-ion batteries due to its low cost, wide source and long lifespan. However, its lower initial Coulombic efficiency (ICE) and poor capacity limit its practical applications. At present, heteroatom doping is an effective strategy to modulate the amorphous carbon microcrystalline structure and improve the sodium storage performance of carbon materials. The synergistic effect generated by combined heteroatom doping is more conducive to enhancing the electrochemical reactivity of carbon materials than single heteroatom doping. In this study, carbon spheres were synthesized by hydrothermal reaction, with waste residue extracted from potato starch processing waste liquid as precursor, based on which boron and nitrogen co-doped biomass carbon spheres were prepared by ball milling and pyrolysis using urea and sodium tetraborate as doping sources. Subsequently, the effects of B and N co-doping on the microstructure and sodium storage properties of carbon materials were investigated. The results indicated that B and N co-doping increased disorder and enlarged layer spacing of carbon materials, while forming suitable C=O bonds that were conducive to stabilizing solid electrolyte interphase film generation. The as-prepared electrode exhibited a reversible capacity of 284.3 mAh·g^-1 at a current density of 50 mA·g^-1 with an ICE of 77.0%. After 500 cycles at 2 A·g^-1, its capacity decayed to 122.5 mAh·g^-1, with 56.1% capacity retention. Therefore, boron and nitrogen co-doped biomass carbon sphere anode material is a promising one for sodium-ion batteries with superior sodium storage properties.

Rapid development of applications in wearable devices, microelectronics, and internet of things has created an urgent demand for free-standing flexible thermoelectric films. Currently, research on n-type free-standing flexible thermoelectric films significantly lags behind, and there is an urgent need to enhance film performance through the optimization of preparation processes. In this study, high-performance n-type poly(vinylidene fluoride)/silver selenide (PVDF/Ag₂Se) free-standing flexible thermoelectric composite films were developed using a simple and efficient powder hot-pressing method. The high-temperature and high-pressure conditions during hot pressing induced recrystallization and grain growth of Ag₂Se, effectively reducing grain boundary density, significantly decreasing carrier scattering and interfacial resistance, thereby simultaneously enhancing carrier mobility, electrical conductivity and Seebeck coefficient. Meanwhile, the melted PVDF filled interstices of the Ag₂Se conductive network during hot pressing, substantially improving material flexibility while increasing density. Experimental results demonstrate that the hot-pressed sample with 80% (in mass) Ag₂Se exhibits outstanding room-temperature thermoelectric performance with an electrical conductivity of 277.0 S·cm^-1 and a Seebeck coefficient of -135 μV·K^-1, and thermoelectric power factor (PF) and estimated figure of merit (ZT) reach 509 μW·m^-1·K^-2 and 0.26, respectively. This performance not only significantly surpasses that of previously reported PVDF/Ag₂Se free-standing films but also ranks among the highest for all reported Ag₂Se-based organic/inorganic free-standing flexible thermoelectric films. Furthermore, mechanical tests reveal that the film maintains over 92% of its original conductivity after 500 bending cycles at a 5 mm radius, while exhibiting a maximum tensile strain four times greater than pure Ag₂Se films. This study provides a novel strategy for synergistic optimization of thermoelectric performance and mechanical flexibility in organic/inorganic composite thermoelectric materials.

Molecular dynamics simulations of high-entropy boride ceramics (HEBCs) in extreme high-temperature environments are constrained by limited accuracy and temperature stability of empirical force fields. In this work, a high-accuracy deep-learning potential (DP) was proposed and developed for (Hf_0.2Zr_0.2Ta_0.2Ti_0.2Nb_0.2)B₂ systems via first-principles calculations and deep learning method. It is shown that, through expanding datasets via the active learning strategy, the DP model stability under high-temperature conditions (i.e., ~3000 K) could be significantly enhanced. The developed DP achieves high accuracy while maintaining computational efficiency. Validation results from the developed DP manifest that predictions of the volumetric equation of state align well with first-principles calculations, demonstrating the model’s good scalability. The lattice constants and mechanical properties predicted by DP-enabled molecular dynamics simulations show excellent agreements with experimental observations, with relative errors within 2%. Furthermore, the simulations successfully reveal the anisotropic thermal expansion behavior of HEBCs and rectify the anomalous trends reported in previous research. Therefore, this developed DP model provides a reliable tool for atomic-scale simulations of high-entropy boride ceramics under extreme conditions, and holds significant scientific value for advancing the in-depth understanding of their high-temperature service behavior.

Continuous fiber-reinforced silicon carbide ceramic matrix composites utilized in hot-section components of high thrust-to-weight ratio aero-engines require protection via thermal/environmental barrier coatings (T/EBCs). To develop novel rare-earth oxide thermal barrier coating materials with low thermal conductivity, compatible thermal expansion coefficients, and excellent high-temperature phase stability, introduction of a high-entropy design concept offers a promising approach and opportunity for composition design and performance optimization. Addressing the challenges of structural modeling and property prediction for complex high-entropy ceramic systems, this study firstly introduces a novel high-entropy ceramic modeling strategy based on the special quasi-random structure (SQS) method. This strategy facilitates rapid prediction of complex ceramic properties while maintaining computational accuracy. Subsequently, crystal structures, elastic properties and thermophysical characteristics of four high-entropy rare-earth oxide materials are predicted and compared by integrating first-principles calculations. This research particularly elucidates regulatory effects and atomic-scale origins of different rare-earth compositions and Hf doping on the material’s low thermal conductivity performance. The research results provide scientific insights and fundamental data for theoretical simulation and material selection design of T/EBCs for aero-engine hot-section components.

Titanium and its alloys are widely used as dental implant materials due to their excellent mechanical property, corrosion resistance and biocompatibility. However, in clinical applications, titanium-based dental implants often suffer from poor soft tissue sealing, allowing bacteria to invade and induce peri-implantitis, and leading to final implant failure. To address these issues and effectively reduce the failure rate of implant surgery, researchers worldwide have conducted extensive and in-depth studies. This article reviews recent advancements in surface modification strategies for improving soft tissue sealing on titanium-based dental implants, with a focus on methods for regulating surface chemical composition and constructing micro-nano structures. Additionally, it highlights the existing challenges and future trends in this field, aiming to provide valuable insights for further research on soft tissue sealing of titanium-based dental implants.

Lanthanum zirconate porous material is a kind of high porosity materials with nanoparticles or microparticles as the basic building unit. These materials exhibit exceptionally low thermal conductivity and maintain remarkable phase stability up to their melting point, making them particularly promising for thermal insulation applications in the aerospace industry. However, sintering problems of lanthanum zirconate porous materials cause collapse and shrinkage of pore structure, resulting in relatively poor thermal resistance and thermal insulation. Researchers have employed precise control over pore sizes and particle dimensions to optimize the mesostructure, leading to a significant reduction in thermal conductivity. Specifically, template-based methods enable precise control over pore sizes at the micro-nano scale, while Sol-Gel techniques combined with varied drying processes facilitate regulation of particle dimensions at the nanoscale. Concurrently, introduction of single- or multi-element doping has proven effective in inducing controlled lattice distortion, which subsequently weakens thermodynamic diffusion processes and suppresses high-temperature grain growth. This dual strategy of morphological control and compositional engineering has substantially improved both thermal insulation capability and temperature resistance of lanthanum zirconate porous materials. This review begins by introducing crystal structure of lanthanum zirconate, highlighting its advantages in phase stability and doping capability. It then systematically surveys recent developments in fabrication technologies and modification strategies for lanthanum zirconate-based porous thermal insulation materials, with particular emphasis on advances in mesostructural optimization and elemental doping methodologies. A detailed analysis is provided on the distinct mechanisms through which these approaches suppress thermal conduction and enhance high-temperature stability. Finally, this review concludes by outlining promising avenues for future research.

Sodium-ion batteries are widely considered a promising alternative to lithium-ion batteries owing to their low cost and the abundance of sodium resources. Advances in development and application of all-solid-state sodium-ion batteries (ASSBs) critically depend on the availability of solid electrolytes that combine high ionic conductivity with wide electrochemical stability window. Among various solid electrolytes, chloride solid electrolytes have attracted considerable attention in recent years due to their high ionic conductivity, high oxidation potential and favorable deformability. This review provides a comprehensive overview of development of sodium chloride solid electrolytes, emphasizing interplay of chemical composition, crystal structure and ionic conductivity, and further examining how modification approaches, including cation/anion doping, amorphization and heterostructure engineering, govern their ionic transport behavior. In addition, this review also evaluates the electrochemical stability of sodium chloride solid electrolytes, and their chemical and electrochemical compatibility with common cathode materials, which are crucial for enabling practical cell configurations. The interfacial degradation mechanisms that arise at the interface with sodium metal anode are also analyzed, and recent advances in chloride-based ASSBs are concisely reviewed. Finally, key challenges that hinder practical deployment of chloride-based ASSBs are highlighted, and prospective research directions are proposed, which are expected to provide valuable insights to guide future application of chloride solid electrolytes in energy conversion and storage technologies.

Carbon fiber-reinforced carbon aerogel (C/CA) composites are one of the most promising candidates for applications requiring both thermal insulation and load bearing capabilities. The preparation of anti-oxidation coatings on C/CA to address its susceptibility to oxidation is a feasible approach to promote its application in oxidative environments. However, the currently reported coatings on C/CA mainly focus on improving the ablation performance and coating preparation process typically necessitating high-temperature heat treatment. This procedure can increase its thermal conductivity and reduce its thermal insulation ability. In this study, a series of ceramic-resin coatings were fabricated on C/CA through a simple slurry brushing-drying approach at room temperature. The effects of phenolic resin content on the coating structure, residual stress, thermal shock, and oxidation behaviors were investigated. Due to the adhesive properties and curing-induced shrinkage, the PR-7.5 coating (containing 7.5% (in mass) phenolic resin in the slurry) exhibits bonding strength close to fracture strength of the substrate and residual compressive stress of 0.853 GPa, which is beneficial for resisting thermal shock cracking. However, excessive resin content (PR-10.0 containing 10.0% (in mass) phenolic resin in the slurry) induces tensile stress due to uneven curing shrinkage, thereby leading to thermal shock cracking. Meanwhile, oxidation tests reveal significantly reduced weight losses for PR-7.5 (17.46% at 800 ℃/100 min, 8.15% at 1000 ℃/120 min, 3.15% at 1200 ℃/120 min) versus uncoated C/CA’s 44.60% loss at 800 ℃/20 min. This work provides a brand-new and simple approach to improving the anti-oxidation performance of C/CA and expands its application in mild oxidative environments.

Commercial phosphor-converted white LEDs (pc-WLEDs) face two inherent limitations, namely blue light hazard and low color rendering index, due to the use of blue LEDs as excitation source. To address these challenges, violet LEDs are proposed as an alternative solution. Currently, phosphors that can be efficiently excited by violet light (with wavelengths from 400 to 420 nm) remain under development still. In this study, we utilize large language models to construct a comprehensive database of Eu²⁺ and Ce³⁺ doped phosphors for discovering novel violet-excited phosphors. A total of 822 phosphor data entries, including elemental compositions, crystal structures and excitation/emission wavelengths, have been extracted and validated from 9551 research papers. Compared with Ce³⁺ doped phosphors, the Eu²⁺ are in general more suited for violet-excited phosphors, as well as red-emitting phosphors. In particular, Eu²⁺ doped nitrides and sulfides are worth of exploration for violet-excited phosphors. This database is expected to be useful in the future development of phosphors for pc-WLEDs based on artificial intelligence methods. The datasets in this article are listed in Science Data Bank at http://doi.org/10.57760/sciencedb.34314.

Methane (CH₄), as both a greenhouse gas and a crucial energy source, plays an important role in achieving China’s carbon peaking and carbon neutrality goals. The significant concentration differences of CH₄ from various sources influence the selection of relevant conversion technologies. However, little research has addressed the impact of CH₄ concentration variation on catalytic performance, and studies focusing on the catalytic pyrolysis of methane for carbon material production are especially scarce. In this work, molten salt catalytic pyrolysis was employed as the core strategy to systematically investigate the catalytic decomposition behavior of CH₄ with varying concentrations (20%-100%) and the morphology control mechanisms of carbon products in a CuCl₂-NaCl molten salt system. The results revealed that the formation of graphene films was attributed to the two-dimensional assembly of carbon atoms on bubble surfaces at high CH₄ concentrations, followed by subsequent film growth. High CH₄ concentration in the CuCl₂-NaCl system favored the formation of well-ordered graphene structures, while low concentrations primarily produced fragmented carbon. Furthermore, various molten salt systems yielded different carbon morphologies, including graphite sheets, short rod-like carbon nanotubes, and film-like carbon. Comprehensive characterizations demonstrated that the CH₄ concentration determined growth mode of the carbon products. This study elucidates morphology control mechanisms of the carbon products driven by the CH₄ concentration gradient in molten salt systems, providing a theoretical basis for the environmentally friendly synthesis of high-value-added carbon materials and development of low-carbon technologies.

Two-dimensional (2D) gallium nitride (GaN) exhibits broad application prospects in the field of ultraviolet optoelectronics due to its dual characteristics of wide-bandgap semiconductor and quantum confinement effect. However, conventional synthesis methods for 2D GaN, such as metal-organic chemical vapor deposition and molecular beam epitaxy, typically require high growth temperatures, prolonged processing time, and relatively high costs. To address these critical challenges, this work leverages the intrinsic properties of liquid metal gallium, including its low melting point and ease of oxidation to develop an efficient and relatively low-temperature synthesis strategy for 2D GaN. The core of this strategy includes following steps. Firstly, utilizing a straightforward spin-coating exfoliation technique to directly extract an amorphous gallium oxide (Ga₂O₃) from the surface of liquid gallium. Subsequently, subjecting the amorphous Ga₂O₃ to a nitridation treatment process at a relatively low temperature of 850 ℃, successfully achieved its conversion into high-crystalline-quality GaN. Characterization results demonstrate that the synthesized 2D GaN possesses a thickness of approximately 2.2 nm, a lateral dimension on the centimeter scale, and a hexagonal wurtzite crystal structure. Furthermore, based on the prepared 2D GaN, a photoconductive ultraviolet photodetector is constructed. Performance characterization results reveal that under a 5 V bias voltage and illumination by 325 nm ultraviolet light, the device exhibits a responsivity of 4.14 A/W and a high detectivity of 1.02×10¹³ Jones. This study demonstrates the successful preparation of large-area 2D GaN material based on liquid gallium metal, providing a valuable reference for the development of low-dimensional and high-performance ultraviolet photodetectors.

KTb₃F₁₀ (KTF) crystal, characterized by its high Tb³⁺ ion concentration, low thermo-optic coefficient and low phonon energy, exhibits significant potential for efficient laser emission in the green and yellow wavelength ranges. However, challenges such as incongruent melting behavior, hygroscopicity of raw materials, high-temperature compositional volatility, and corrosive nature of fluorides have severely hindered the growth of high-quality KTF crystals. This study aims to develop an effective approach to address these issues, achieve the growth of high-quality KTF crystals, and characterize their optical properties. An optimized vertical Bridgman method integrated with a laser-sealed platinum crucible technique under vacuum was employed. This innovative approach effectively shielded the raw materials from water and oxygen contamination while suppressing compositional deviation during crystal growth through a sealed environment. As a result, blank KTF crystals with dimensions of φ16 mm×30 mm were successfully grown, and their relevant spectral properties were characterized. X-ray rocking curve of the (111) plane showed a full width at half maximum of 0.08°, indicating high crystalline perfection. Thermal analysis indicated significant volatilization of KTF at high temperatures. Spectral tests revealed an average transmittance of >90% in the 400-1600 nm range and an absorption coefficient of <0.007 cm^-1 at 1064 nm, demonstrating minimal optical loss suitable for high-power laser applications. Fluorescence lifetime was 4.82-4.99 ms for the Tb³⁺ ion at the ⁵D₄ energy level, which is 3-5 times longer than that in oxide matrices. This superiority is attributed to the suppression of non-radiative relaxation by the low-phonon fluoride matrix, enhancing the energy storage efficiency for laser emission. Based on above data, this study has successfully established a viable growth method for KTF crystals, providing a new technical pathway for the controllable synthesis of KTF and other ternary fluoride materials. All these results provide valuable insights for the high-efficiency application of KTF crystals in yellow-green laser emission.

BN ceramic fibers exhibit significant potential for applications in high-temperature wave-transparent and semiconductor fields, due to their excellent resistance to high temperatures and thermal conductivity, as well as their outstanding wave-transparent performance. However, the low crystallinity observed in BN ceramic fibers inhibits complete realization of their potential superior properties associated with the h-BN crystal structure. In this work, based on the mechanism that inorganic nanofillers could act as heterogeneous nucleating agents to accelerate matrix crystallization, three lateral sizes (0.5, 2 and 4 μm) of amino-functionalized BN nanosheets (BNNSs) were prepared utilizing a one-step ball milling method. BNNSs were chemically bonded to molecular chain of polyborazine to synthesize hybrid BNNS/polyborazine precursors, which were finally derived into high-performance BN ceramic fibers with high crystallinity. This investigation thoroughly explored the scale effects of BNNS on the molecular structure of hybrid precursor, as well as their physicochemical properties and melt spinning performance. Relationship among the BNNSs’ size, microstructure and mechanical properties was elucidated. Increasing BNNSs size could enhance the ceramic yield of precursor (up to 64.1%), but destroy the viscosity-time stability. Moreover, it was demonstrated that BNNS scale could evidently regulate crystal structure of BN ceramic fibers. Relationship among the BNNSs’ lateral sizes, crystal structure and mechanical performance was determined to be non-linear. BN ceramic fibers containing 2 μm BNNS displayed the highest crystallinity (94%), grain size (12.5 nm) and density (2.00 g/cm³). However, surface defects associated with 2 μm BNNS resulted in a non-optimal average tensile strength (0.90 GPa). BN ceramic fibers doped with 0.5 μm BNNS exhibited the best average tensile strength (0.94 GPa), attributed to the favorable combination of high crystallinity and smooth surface. This work could provide crucial references for fine regulation of microstructure and preparation of high-performance BN ceramic fibers.

Under demanding service conditions, the operational requirements, namely high-temperature performance and structural weight reduction, in aero-engine hot section components continue to intensify. Silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composites are widely recognized as exceptionally promising alternative materials owing to their outstanding high-temperature stability, substantially reduced density and superior corrosion resistance. However, in actual service environments, these composites inevitably experience complex vibrational loading spectra, which induce fatigue damage accumulation emerging as a critical limiting factor in their practical engineering implementation. In this study, 2D SiC/SiC plates were fabricated by chemical vapor infiltration. Specimens featuring bilateral arc-shaped notches were machined from the plates and subsequently subjected to narrow band random vibration fatigue tests under the first-order vibration mode. This experimental approach was undertaken specifically to investigate the progressive damage evolution process and the accompanying degradation patterns in tensile properties under vibrational fatigue loading. The experimental findings reveal that the normalized full time-domain characteristic curves of the 2D SiC/SiC plate structures exhibit progressive downward displacement while the applied equivalent stress amplitude increases. These curves concurrently manifest pronounced statistical dispersion throughout low-stress loading regime. Based on microstructural analyses, the damage evolution within the 2D SiC/SiC plate structure can be classified into three distinct and sequential stages: the initial matrix damage stage, the subsequent interface damage stage, and the final fiber damage stage. Quantitatively, the damage progression rate follows a distinct correlated three stage evolution—commencing with rapid progression, then transitioning to reduced propagation velocity, and lastly culminating in accelerated damage advancement. Residual tensile properties demonstrate that the tensile characteristics of the 2D SiC/SiC plate structure follow an exponential decline trend. At a resonance frequency reduction of 31.9%, the tensile strength, proportional limit stress, elastic modulus, and resilience modulus have degraded to 270.0 MPa, 64.1 MPa, 106.3 GPa, and 0.020 MJ/m³, respectively, all falling below 70% of the corresponding values in the as-fabricated pristine state. Subsequent analyses of the tensile fracture surface reveal matrix cracking and pronounced fiber wear as the dominant damage mechanisms responsible for the significant degradation observed in the tensile properties of the vibration fatigued composite structure. These findings provide a critical experimental basis for assessing the service reliability of 2D SiC/SiC plate structures under vibrational service conditions.

SiC_f/SiC composites exhibit advantages such as high-temperature resistance, oxidation resistance and high strength, making them a “star” candidate material in the field of aerospace thermal protection. Under operational conditions, these materials are subjected to prolonged multiple coupled fields such as heat, water and oxygen, exhibiting complex failure mechanisms and damage evolution patterns. This study investigated the integrated oxidation mechanism of the matrix/interface/fiber in Mini-SiC_f/BN/SiC composites under cyclic oxidation at 1100 ℃ in a water-oxygen coupled environment by using multi-scale macro/micro characterization techniques. The results showed that during the initial oxidation stage, an amorphous SiO₂ glass layer with relatively smooth morphology formed on the material surface. However, with an increase in crystallinity, localized spallation occurred in the oxide layer, causing the surface roughness to initial decrease and subsequent increase. X-ray microscope results showed that numerous micro-defects were generated within the material after cyclic oxidation, and the number of defects increased by orders of magnitude (about 107 fold). Majority of these micro-defects were mainly distributed on the matrix surface, and the oxidation products played a certain filling role in these defects. The tensile strength showed no significant variation before ((328.47±32.84) MPa) and after ((343.27±35.71) MPa) cyclic oxidation, indicating continued effectiveness of the synergistic toughening mechanism of “strong matrix-weak interface”. These observations indicate that an integrated oxidation protection mechanism involving matrix, interface and fiber exists in the Mini-SiC_f/BN/SiC, which is predicated on the filling of defects by SiO₂ and borosilicate glass generated by its interface layer and adjacent matrix with fibers in the direction parallel to the fiber axis. Dynamic “outer porous sacrificial layer-middle dense SiO₂-inner SiC matrix” is a three-dimensional protective barrier of the matrix in the direction perpendicular to the fiber axis. This dual-protection system substantially alleviates material degradation under cyclic thermal water oxidative conditions.

Continuous alumina fiber-reinforced silica ceramic matrix composites exhibit excellent properties, such as high-temperature oxidation resistance, high strength and high toughness. As a dual-use material for both military and civilian applications, they hold broad prospects in numerous fields, including aviation, aerospace and energy. However, domestic research currently still remains on its initial stage and is characterized by a primarily qualitative understanding of their mechanical property failure mechanisms. In this study, an improved liquid-phase impregnation method, which integrated the process characteristics of the Sol-Gel method and slurry impregnation method, was adopted to prepare continuous alumina fiber-reinforced silica composites with tunable porosity. Microstructure and composition of the typical composite were comprehensively characterized using different techniques. Mechanical properties of these composites with different densification degrees were tested and analyzed. By integrating porosity data obtained from computed tomography (CT) test with simulation calculation, a relationship model linking mechanical property failure of the composites to porosity and pore size parameters was established. The results indicated that composites prepared via the improved liquid-phase impregnation method had significantly enhanced mechanical properties due to the presence of pore defects and weak interfacial bonding. Notably, as the composite porosity increased from 2.2% to 15.2%, the tensile strength decreased from 24.5 MPa to 17.8 MPa. Further modeling and simulation analysis revealed that, at a pore defect radius of 250 μm, an increase in porosity from 4.5% to 13.5% led to a corresponding reduction in tensile strength from 27.2 MPa to 20.6 MPa, thereby validating rationality of the simulation model. The law that the n-th power of tensile strength shows a negative linear correlation with porosity, and the tensile strength exponent factor n is negatively linearly correlated with the pore defect radius r. These findings provide a research basis for the performance optimization and practical application of continuous alumina fiber-reinforced silica composites.

Gen IV nuclear reactors operate in extreme service environments characterized by high temperature and intense irradiation, imposing stringent demands on structural materials and thus necessitating the development of novel irradiation resistant materials. Titanium carbide (TiC_x) ceramic is considered as promising structural material for advanced nuclear reactors, attributed to its high melting point, excellent mechanical properties, and excellent corrosion resistance. In this study, TiC_x films with different stoichiometries were irradiated with 3 MeV Au²⁺, aiming to systematically investigate irradiation-induced changes in structural characteristics, surface morphology and mechanical properties under different irradiation fluences. The results revealed that structural disorder of TiC_x intensified with increasing irradiation fluence, while the substoichiometric TiC_x maintained superior structural stability after irradiation. Surface roughness of substoichiometric TiC_x showed no significant variation after irradiation, with no irradiation-induced crack. Additionally, both hardness and elastic modulus of TiC_x exhibited an increasing trend after irradiation, demonstrating that substoichiometric TiC_x enhanced resistance to irradiation compared to near-stoichiometric counterparts. The native carbon vacancies in substoichiometric TiC_x effectively suppress accumulation of irradiation-induced defects, thereby preserving excellent stability. This study provides critical insights into the relationship between stoichiometry and irradiation damage in TiC_x, while offering valuable guidance for designing new classes of irradiation-resistant ceramic materials.

Silicon carbide (SiC) is a promising material for nuclear reactor structures due to its excellent radiation resistance and high-temperature performance. The behavior of irradiation damage and the mechanisms of high-temperature recovery in SiC directly affect its service performance and longevity in nuclear environments. This study investigated effects of neutron irradiation on properties of 6H-SiC, with a particular focus on high-temperature recovery mechanisms of irradiation-induced defects. Specifically, defect evolution and thermodynamic responses in nitrogen-doped (N_D≈3.0×10¹⁹ cm^-3) 6H-SiC subjected to neutron irradiation at about 150 ℃ and a fluence of 2.58×10²⁰ n/cm² followed by isochronal annealing were examined. Integrated techniques and first-principles calculations were employed to comprehensively analyze its structural and property evolution. The key findings were as follows. (1) Significant lattice swelling was observed during the irradiation, with a swelling rate of 0.416% along the a-axis, 0.430% along the c-axis, and 1.310% in the unit cell volume, while all maintaining integrity of the single-crystalline structure. (2) A 14.7% increase in specific heat capacity was recorded, with 375.4 J/g of stored irradiation energy being released during heating from 100 ℃ to 500 ℃. (3) A four-stage defect recovery kinetic model was proposed based on the recovery of lattice parameters and the evolution of Raman spectra: Stage I (room temperature (RT)-600 ℃), primarily dominated by close-range recombination of carbon Frenkel pairs driven by migration energy (E_a) of 0.14 eV; Stage II (600-850 ℃), recombination of silicon Frenkel pairs and migration of carbon interstitials (E_a=0.26 eV); Stage III (850-1200 ℃), lattice reconstruction (E_a=0.65 eV); Stage IV (1200-1500 ℃), long-range diffusion of carbon vacancies (V_C) and dissociation of N_CV_Si complexes (E_a=1.50 eV). (4) The presence of nitrogen-stabilized N_CV_Si defect configurations was confirmed by a characteristic emission peak at 826 nm (634 cm^-1 Raman shift) when excited with 785 nm light. This study quantitatively reveals the defect recovery pathways and migration energies in neutron-irradiated 6H-SiC, providing a critical foundation for evaluating radiation damage, predicting performance, and optimizing annealing processes in nuclear-grade SiC materials.

Thermomagnetic refrigeration based on the Ettingshausen effect is a low-temperature solid-state cooling technology with advantages of precise temperature control, compact size and noiseless operation. In recent years, topological semimetals, which possess both electrons and holes as charge carriers and exhibit high carrier mobility, have shown excellent thermomagnetic performance at low temperatures, making them promising candidates for cryogenic applications. In this study, highly dense polycrystalline TaSb₂ was synthesized via solid-state reaction followed by spark plasma sintering, and its low-temperature thermomagnetic transport properties were systematically investigated. The results show that the Nernst thermopower (S_yx) peaks at around 27 K and increases with applied magnetic field. Under 9 T and 26 K, the Nernst power factor ((PF)_N) reaches 315.1 μW·cm^-1·K^-2, while under 9 T and 22 K, the Nernst figure of merit (z_N) is 7.1×10^-4 K^-1, both outperforming most reported polycrystalline thermomagnetic materials. Mechanistic analysis indicates that the high performance originates from the combined effects of strong bipolar effect, high carrier mobility and significant phonon-drag enhancement of thermopower. Moreover, magnetic fields markedly suppress the electronic contribution to thermal conductivity at low temperatures, making the total thermal conductivity predominantly determined by the lattice component. This work offers a new material option and design strategy for low-temperature solid-state cooling applications. The relatively high lattice thermal conductivity partially limits the thermomagnetic performance, and further reduction via phonon engineering could lead to substantial improvements.

NiMn-layered double hydroxide (NiMn-LDH) is a promising cathode material for hybrid supercapacitors (HSCs) due to its inherent environmental sustainability, exceptionally high theoretical specific capacitance, and robust cycling stability. However, its widespread practical application faces significant limitations due to its poor electronic conductivity, which results in low specific capacitance and rate capability. Particularly at mg·cm^-2 magnitude loading, the specific capacitance at high current densities of 50 A·g^-1 or above is much lower than 1500 F·g^-1, a performance threshold critically insufficient for the energy-power balance required in commercial HSC devices. To address this limitation, this work innovatively developed a novel NiMn_x-LDH@Ni₉₅Cu₅ electrode via a simple two-step electrodeposition strategy. Ni₉₅Cu₅ dendritric foams with hierarchical porous structure were prepared by hydrogen bubble template method, and NiMn-LDH was anchored to the Ni₉₅Cu₅ substrate by electrochemical deposition. By adjusting the Mn/Ni stoichiometric ratio in NiMn-LDH which was electrodeposited on the surface of Ni₉₅Cu₅ dendritic foam through variations of the metal ion ratios in electrodeposition solution, its influence on the composition, elemental valence state, crystal structure, morphology, energy band configuration, and electrochemical behavior of NiMn-LDH was investigated. As the Mn content in NiMn-LDH increases, the size of NiMn-LDH nanosheets decreases. The optimized NiMn_0.6-LDH@Ni₉₅Cu₅ electrode exhibits superior crystallinity, minimized charge-transfer resistance, the narrowest band gap, and synergistically exceptional electrochemical performance, delivering outstanding specific capacitances of 2365 F·g^-1 at a current density of 1 A·g^-1 and 1803 F·g^-1 at an ultrahigh current density of 50 A·g^-1, even under high mass loadings (>2 mg·cm^-2). Furthermore, it demonstrates remarkable cycling stability and retains 88.8% of its initial capacity after 3000 cycles at 20 A·g^-1. Collectively, this study confirms that the composition, crystallinity and energy band structure of LDH can be synergistically optimized by precisely tuning the bimetallic ratio, thus solving the problem of specific capacitance and multiplicity performance degradation of high-loading electrodes, and provides a new idea for the design of next-generation high-performance HSC electrodes.

Oxygen reduction reaction (ORR) is an important cathodic reaction, but its slow reaction kinetics seriously hinders the application of clean energy devices such as fuel cells and metal-air batteries. Although platinum (Pt)-based catalysts possess excellent ORR activity, their high cost, scarce reserves, poor stability and tolerance make it difficult to commercialize current clean energy technologies. To address the above problems, it is urgent to develop new types of efficient and low-cost ORR catalysts. As an emerging carbon-based material, nanodiamond (ND) exhibits broad application prospects in ORR catalysis due to its advantages such as low cost, controllable functional group modification, high surface energy (>1000 mJ·m^-2), and unique π and σ bond configurations. This paper reviews the latest research progress of ND catalysts. Firstly, preparation methods such as detonation, chemical vapor deposition, pulsed laser ablation, and high-pressure high-temperature are introduced. Subsequently, modification strategies including heteroatom doping, surface functionalization, material composite, and morphology regulation are summarized, and their formation mechanism of active centers and regulation rules of reaction paths are analyzed, covering influence of different modification strategies on catalytic performance and comparison of relevant performance data. Finally, the challenges faced by current ND catalysts in catalytic mechanism, synthesis process, characterization technology, and design methods are analyzed to suggest the future development directions for the research and development of new carbon-based ORR catalysts.

Silica aerogel has broad applications in the field of high-temperature thermal insulation due to its low density, low thermal conductivity and high stability. However, its thermal insulation performance deteriorates significantly at elevated temperatures exceeding 600 ℃, primarily due to the collapse of pore structure. Meanwhile, the shielding capacity of SiO₂ aerogel to the infrared radiation at high temperature is rather low due to the intrinsic properties of SiO₂. Herein, a strategy for improving the high-temperature stability and infrared shielding properties of SiO₂ aerogel via Ca doping was explored. Calcium-doped silica aerogel (CSA) powders were prepared by Sol-Gel, hydrothermal, and ambient pressure drying (APD) techniques using water glass and anhydrous calcium chloride as precursors and trimethylchlorosilane as a hydrophobic modifier. The effects of Ca/Si molar ratio in the precursor and hydrothermal conditions (temperature and pH) on the crystalline properties, microscopic morphology and pore structure of CSAs were investigated. The results show that the Ca/Si molar ratio and hydrothermal treatment have significant effects on the microstructure and heat resistance of CSAs in the temperature range of 400-1000 ℃. The samples sintered at 1000 ℃ have a high specific surface area of 100.1 m²/g and a pore volume of 0.8705 cm³/g, indicating that the CSA has good heat resistance. One-side insulation tests at temperatures up to 600 ℃ show that the sample with a Ca/Si molar ratio of 1.0 has the best insulation performance, with a cold surface temperature of 450 ℃, which is 27 ℃ lower than that of the pure silica aerogel.