Ultra-high temperature ceramic (UHTC) structural materials have emerged as critical candidates in the fields of aerospace, defense equipment, energy and power sectors due to their outstanding oxidation/ablation resistance, high-temperature strength retention, and thermal shock resistance in oxidative environments exceeding 1600 ℃. In recent years, extensive research has been achieved in both fundamental research and technological applications focusing on compositional control, structural design, fabrication techniques, and performance optimization of these materials. UHTC systems, characterized by carbides, borides and nitrides, are currently facing increasingly stringent demands for enhanced thermal performance in more complex environments. To further advance development of UHTC structural materials for such conditions, this paper systematically reviews the latest research progress in this field. Firstly, synthesis techniques of UHTC powders are elaborated. Subsequently, systems, densification methods and structural regulation strategies of UHTCs are presented. Furthermore, fabrication techniques and performance enhancement strategies of UHTC matrix composites (UHTCMCs), UHTCs modified carbon/carbon composites (UHTCs-C/C), and UHTC coatings are examined, with particular emphasis on the latest breakthroughs in oxidation/ablation resistance. Additionally, primary technical challenges related to the long-term stability and reliability of UHTC structural materials under extreme conditions are identified, and a forward-looking perspective on future development trends is provided.

Lithium niobate (LiNbO₃, LN) is an artificial crystal with excellent physical properties, such as acousto-optic, electro-optic, piezoelectric, and photorefractive performance. It is not only seen as "optical silicon", but also suggests that humans are entering the era of "Lithium Niobate Valley". Its excellent optoelectronic properties have a wide potential application in emerging fields, such as artificial intelligence and photoelectric hybrid module. Photorefraction was found and proved to be an important property of LN crystal. With development of optoelectronic devices based on LN to micro- and nano-scale, photorefractive effect has gradually appeared. Single crystal LN is the basic material for preparing various devices taking advantage of lithium niobate on insulator (LNOI). The photorefractive properties can be adjusted by doping appropriate impurity ions. Compared with normal ions (valence < +5 (valence of niobium ions)), incorporation of high-valence ions (valence ≥ +5) can be more beneficial to improve photorefractive performances of LN crystals in recent years. This paper summarizes research progress of high-valence ion-doped LN crystals of which doping with V, Mo, U, and Bi ions can effectively adjust their photorefractive properties, suitable for designing micro-ring resonators, optically programmable photonic components, nonlinear photonic devices, and other micro- and nano-scale devices. Finally, based on above advances in high-valence ion doped LN, further research may achieve unprecedented improvements in four aspects: high-quality and big-size crystal growth, photorefractive mechanism, ion doping with lone-pair electrons, and novel optoelectronic devices.

X-ray induced photochromic (XP) materials, characterized by their radiation dose-dependent coloration properties, exhibit broad application potential in national defense and security, nuclear energy development and utilization, industrial nondestructive testing, and medical imaging. In recent years, scientists worldwide have developed diverse XP material systems, conducted in-depth investigations into their radiation-induced coloration mechanisms, and explored their specialized applications, highlighting the urgent need for a comprehensive review on their working principles and application domains. This article systematically summarizes the material systems exhibiting XP behavior, categorizing them based on chemical composition and coloration characteristics. Their advantages and limitations are comparatively analyzed, while their underlying mechanisms, such as color center formation and redox processes, are analyzed. Furthermore, their potential applications in X-ray detection, medical diagnostics, and industrial monitoring are introduced. Finally, their future research directions are proposed to develop new XP materials with enhanced performance and broader scenario adaptability. This review holds significant implications for guiding subsequent research on optimizing XP materials and accelerating their commercialization process, thereby facilitating the practical implementation of XP technologies.

Key components of aerospace power systems operating under extreme conditions, such as high loads, elevated temperatures, oxygen-rich environments, and wide-temperature-range alternating thermal shocks, impose stringent requirements on material mechanical properties, thermal stability, and oxidation resistance. Conventional thermally sprayed Al₂O₃ coatings, characterized by high hardness, excellent wear resistance, superior oxidation resistance, and good thermal stability, have been widely applied to aerospace, energy, and mechanical engineering fields. However, these coatings primarily consist of metastable γ-Al₂O₃ as the dominant crystalline phase, which exhibits inferior mechanical and thermal conductivity properties compared to α-Al₂O₃. This limitation hinders their effectiveness under extremely high-load conditions. To address this issue and enhance the overall coating performance, atmospheric plasma spraying (APS) was employed to fabricate Al₂O₃-GdAlO₃ (GAP) amorphous coating with a thickness of approximately 350 µm. The friction and wear behavior, along with the mechanical properties of the coating, were systematically investigated through a designed wear test under a load of 2000 N, a rotational speed of 500 r/min, and a duration of 1 h. Experimental results indicate that due to the high proportion of the amorphous phase and the optimized microstructure, the Al₂O₃-GAP coating exhibits excellent wear resistance and superior crack propagation resistance under high-speed and heavy-load friction conditions, significantly outperforming conventional polycrystalline Al₂O₃ coatings. Furthermore, the Al₂O₃-GAP coating demonstrates a lower and more stable friction coefficient, effectively reducing frictional surface temperature. This mitigates high-temperature oxidation and thermal damage while alleviating stress concentration effects. In summary, the Al₂O₃-GAP amorphous coating demonstrates remarkable advantages under high-load, high-speed friction conditions, providing a high-performance and reliable coating solution for the protection of critical aerospace power system components.

SiC/SiC ceramic matrix composites (SiC/SiC CMCs) are expected to be used in the thermal protection system of reusable aerospace vehicles due to their advantages of high temperature resistance, low density and high strength. Given the complex and harsh working environment of aerospace vehicles, it is urgent to develop a high-temperature anti-oxidation sealing coating on the surface of SiC/SiC CMCs to meet the requirements for reusability. In this work, a SiC transition layer was designed and prepared on the surface of SiC/SiC CMCs by chemical vapor deposition (CVD), which is supposed to solve the cracking and spalling problems of the MoSi₂-doped SiO₂-Al₂O₃-BaO-B₂O₃ (MoSi₂-SABB) glass-ceramic composite coating, and enable the coating to exhibit excellent thermal shock resistance. Finite element analysis showed that the SiC transition layer could effectively reduce the residual stress at the interface between the MoSi₂-SABB coating and the substrate, alleviate anisotropy of the residual stress, and significantly improve bonding performance of the coating. This binding mechanism of SiC transition layer with different crystal structures and polarities and MoSi₂-SABB coating was investigated by the first principles calculation. The results showed that crystal structure and polarity of SiC transition layer were key factors affecting the coating bonding performance, providing a basis for design and optimization of bonding performance for surface sealing coating of SiC/SiC CMCs.

As a new type of photothermal compound, bismuth-based nanomaterials have advantages of low toxicity, environmental friendliness, and cheap raw materials, showing great application potential in biological photothermal therapy, but their photothermal conversion efficiency and antibacterial property are still low. In this study, based on the confined gelation method reported by previous literature, a silica-based hybrid micellar precursor with organosilica- stabilized micellar cores was prepared using Pluronic polymer F127 and 3-mercaptopropyl-trimethoxy-silane as raw materials, and a facile “confined reduction/sulfuration” method was further developed, that is, the abundant thiol groups in the organosilica framework of the micelle core were used as restricted adsorption sites, sodium borohydride was used as reducing agent, and sodium sulfide was used as vulcanizing agent to prepare ultra-small and amorphous bismuth sulfide clusters-supported silica-based hybrid micellar system. The results show that the functional hybrid micellar system has excellent photothermal performance, and its photothermal conversion efficiency is up to 86.93%, which may be attributed to monodisperse and stable loading of bismuth sulfide clusters with defective structure in the organosilica framework of hybrid micellar system, which enhances light absorption capacity of bismuth sulfide nanomaterials in the near-infrared wavelength range. The in vitro antimicrobial experiments show that this bismuth- containing system exhibits excellent photothermal antibacterial properties under irradiation of 808 nm near-infrared laser and good biocompatibility.

Bone implant-related infections are characterized by a high risk of delayed incidence or recurrence. Current antibacterial strategies often lack selectivity, leading to collateral damage to normal tissues and cells during bacterial eradication. To address this, mesoporous bioactive glass (MBG) was used as a base material in this study. By leveraging the near-infrared (NIR) photothermal response of S-NO bonds to release NO radicals and the antibacterial properties of Cu²⁺, MBG-RSNO powder was synthesized through amino-functionalized conjugation of S-nitrosothiols (RSNO) for nitric oxide free radicals (NO·) delivery, while PMBG@Cu powder was prepared via dopamine polymerization and Cu²⁺ chelation. These two powder materials were further processed through 3D printing to fabricate a PMBG@Cu/MBG-RSNO composite antibacterial scaffold. This scaffold demonstrated a strong NIR photothermal response, with pulsed 808 nm laser irradiation enabling the sustained release of NO· up to 113.71 μg per 100 mg of MBG-RSNO and increasing the temperature to approximately 40 ℃, facilitating efficient bacterial elimination. Antibacterial performance of the scaffold was evaluated using Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) as representative Gram-positive and Gram-negative bacteria, respectively, with and without external NIR stimulation. The results revealed that the PMBG@Cu/MBG-RSNO composite scaffold achieved an antibacterial efficiency of 99.9% against both bacterial strains. In summary, the PMBG@Cu/MBG-RSNO composite scaffold offers a promising solution to address infection challenges in bone implant materials and supports bone defect repair.

Carbon fiber/polyetheretherketone (CF/PEEK) has been widely used in the field of bone repair. However, its bio-inert nature results in poor osseointegration, which significantly limits its long-term stability and bone repair efficacy in clinical applications. Here, a manganese-doped nano-hydroxyapatite (Mn/nHA) coating was constructed on the surface of CF/PEEK using a liquid-phase self-assembly strategy of inorganic nanoparticles. The experimental results demonstrated that both Mn/nHA and nHA coatings significantly improved the surface roughness and hydrophilicity of CF/PEEK. Further in vitro studies revealed that after co-culturing with rat mesenchymal stem cells (BMSCs) for 7 d, the relative cell viability of the Mn/nHA- and nHA-coated materials reached as high as 180% and 159%, respectively, indicating a pronounced pro-proliferative effect. Additionally, alizarin red staining and reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that both coatings enhanced cell mineralization and osteogenic differentiation on the material surface, with the Mn/nHA coating exhibiting a stronger promoting effect.

In a high heat flux ablative environment, the surface temperature of aircraft rises rapidly, leading to traditional high thermal conductivity materials being ineffective at protecting internal metal components. In this study, continuous carbon fiber reinforced Li₂O-Al₂O₃-SiO₂ (C_f/LAS) glass ceramic composites doped with SiC particles (SiC_p) were prepared by slurry immersion winding and hot pressing sintering. Effect of matrix crystallinity on ablative properties of the composites under ultra-high heat flux was investigated. By utilizing heat absorption and low thermal conductivity characteristics associated with SiO₂ gasification within composite materials, both surface and internal temperatures of these materials are effectively reduced, thereby ensuring the safe operation of aircraft and electronic devices. Results indicate that the average linear ablation rate of composites doped with 10% (in mass) of SiC_p significantly decreases at a heat flux of 20 MW/m². Transmission electron microscope observation reveals that the doped glass matrix exhibits increased crystallinity, reduced internal stress, and minimized lattice distortion, thereby enhancing the composites’ high-temperature performance. However, excessive SiC_p doping leads to reduced crystallinity and deteriorated ablation performance. Ultimately, the average linear ablation rate of C_f/LAS composites with 10% (in mass) SiC_p at 20 MW/m² heat flux is comparable to that of commercial carbon/carbon composites, accompanied by providing lower thermal conductivity and higher bending strength. This novel high-performance C_f/LAS composite is cost-effective, short-cycled, and suitable for mass production, offering promising potential for widespread application in ablation-resistant components of hypersonic vehicles.

Electrochromic (EC) smart windows utilizing a reversible metal electrodeposition device (RMED) offer a compelling alternative for dynamically regulating transmissions of optical and thermal energy. An EC device (ECD) is constructed by reversible metal electrodeposition (RME) of Bi/Cu on WO₃·xH₂O film electrodeposited onto fluorine-doped tin oxide (FTO) transparent conductive glass. The electrolyte consists of CuCl₂, BiCl₃, KCl and HCl aqueous solution, supplying necessary components for both electrochemical and electrodeposition processes. The ECD shows ability to rapidly transition between colorless and black states, which achieves a large optical modulation of 77.0% at 570 nm. In the black state, the ECD exhibits a near-zero transmittance in the wavelength range of 400-1100 nm while maintaining 96.6% of its initial optical modulation after coloration/bleaching cycling of 60000 s, exhibiting good cyclic stability. This RMED has relatively high stability under open-circuit voltage and also possesses excellent heat insulation performance. The results offer a solution to overcome the poor cyclic stability of RMEDs and improve the optical modulation of ECDs.