ABSTRACT The rapid advancement of power electronics has created an urgent demand for high‐permeability, low‐loss soft magnetic materials to unlock the full potential of wide‐bandgap semiconductors and improve the efficiency of switching‐mode power supplies. In this work, innovative soft magnetic composites are constructed with ordered quasi‐two‐dimensional (2D) Finemet flakes featuring a reduced out‐of‐plane size from ∼18 to ∼1 μm, leading to an 80% increase in permeability, a 60% reduction in core loss, and a fivefold enhancement in cut‐off frequency. These improvements are correlated with the enhanced magnetization behavior of particles characterized by increased response intensity and resonance frequency for both domain wall motion and spin rotation. Furthermore, finite element simulations reveal that such geometrical optimization plays a critical role in enhancing the magnetization homogeneity of the particles. This work not only reveals the structure‐property relationship for the composites constructed from quasi‐2D soft magnetic particles but also elucidates a geometrical modulation mechanism for improved soft magnetic performance of nanocrystalline soft magnetic composites in MHz applications.
ABSTRACT Solid oxide electrolysis cell (SOEC) technology is a promising route for efficient and clean green hydrogen production because of its high conversion efficiency and the use of precious‐metal‐free catalysts. However, developing oxygen electrodes that combine high electrochemical activity with robust long‐term operational stability remains challenging. Ultrasonic spray pyrolysis (USP), as a scalable and controllable synthesis strategy, enables the fabrication of oxygen electrode composites with hierarchical pore structures and tunable chemical compositions. Taking the rare‐earth‐containing La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3– δ ‐Gd 0.2 Ce 0.8 O 2– δ (LSCF‐GDC) composite as an example, the nanostructured oxygen electrode prepared via USP exhibits a uniformly distributed porous microstructure and intimate interfacial contact between the LSCF and GDC phases. Notably, the optimized LSCF‐GDC oxygen electrode with a mass ratio of 7:3 exhibits excellent reversible bifunctional electrochemical performance at 800°C. In SOEC mode, the cell achieves a current density of 636 mA cm −2 at 1.3 V, whereas the operation of the same cell in reversible SOFC mode yields a peak power density of 1090 mW cm −2 . Furthermore, the full cell exhibits negligible voltage degradation during continuous reversible operation, which is attributed to the robust nanostructured electrode architecture that effectively suppresses particle coarsening and phase segregation during prolonged high‐temperature cycling. These results demonstrate the effectiveness of USP‐induced structural modulation for constructing durable and highly active oxygen electrodes for reversible solid oxide electrochemical cells.
ABSTRACT Silicon carbide (SiC) is an ultra‐hard ceramic material and is intrinsically difficult to sinter. Pressureless solid‐state sintering (PS) typically requires high temperatures exceeding 2200°C and a prolonged heating cycle, whereas liquid‐phase sintering lowers the processing temperature at the expense of high‐temperature mechanical performance. Field‐assisted routes such as spark plasma sintering (SPS) and flash sintering have been explored, yet it is still challenging to produce reliable ceramics with improved flexural strength and fracture toughness. Here we report a field‐assisted solid‐state sintering strategy in which electrical current directly flows through the SiC compacts, enabling densification at 1650°C within 2 h. The applied electric field has two roles: voltage‐driven in situ graphitization of organic binders in granulated SiC powders and large current flowing through the sample to enhance densification. The produced SiC ceramics with in situ graphitized carbon have an exceptional flexural strength of 625 MPa at room temperature and 746 MPa at 1400°C, a high fracture toughness of 5.0 MPa m 1/2 , and a low electrical resistivity of 9.6 Ω cm, which is four orders of magnitude lower than that of conventional SiC ceramics. This work establishes a new field‐assisted sintering route to access strong and electrically conductive forms of SiC ceramics and offers new opportunities for accelerated processing of high‐temperature ceramics.
ABSTRACT Defect engineering plays a crucial role in regulating the active sites and reaction pathways of nanozymes. In this work, oxygen vacancies (Vo) were successfully introduced and stably regulated in ternary CoFeMo layered double hydroxide (CFM LDHs) via a microwave‐assisted hydrothermal strategy, leading to the construction of oxygen‐vacancy‐rich CFM‐LDH nanosheets (CFM‐Vo LDHs). Density functional theory (DFT) calculations reveal that the presence of oxygen vacancies not only induces local lattice distortion and electronic structure redistribution but also optimizes the adsorption behavior of key intermediates. As a result, the peroxidase (POD)‐like catalytic process is transformed from a single reaction pathway into dual reaction channels, significantly accelerating the decomposition of H 2 O 2 to generate •OH and thereby enhancing the overall catalytic kinetics. Benefiting from the enhanced POD‐mimicking activity, a colorimetric sensing platform based on CFM‐Vo LDHs was constructed for the highly selective detection of nitrite (NO 2 − ) and aflatoxin B1 (AFB1). The sensing system exhibits a favorable linear response, excellent anti‐interference capability, and robust detection stability, with detection limits of 0.56 μM and 0.084 ng mL −1 , respectively. Furthermore, by integrating smartphone‐based color recognition with a machine learning model, rapid and accurate on‐site quantitative analysis of the target analytes was achieved. This study reveals the intrinsic mechanism by which oxygen vacancies reconstruct the POD‐like catalytic reaction pathway, providing a new materials strategy for the rational design of high‐performance LDH‐based nanozymes and expanding their application potential in food safety monitoring and environmental analysis.
ABSTRACT High‐temperature microwave‐absorbing materials (HTMAMs) are vital for the electromagnetic stealth of hypersonic aircraft and aerospace engines. Traditional carbon‐based or magnetic‐based absorbers suffer from oxidation, Curie‐temperature limitations, and impedance mismatch under extreme conditions. Rare metals, including rare light metals, rare refractory metals, rare dispersed metals, and rare earth metals, offer unique electronic configurations, desirable high‐temperature stability, and tunable electromagnetic properties. Therefore, the integration of rare metals enables effective high‐temperature microwave absorption. This review systematically summarizes the advances in HTMAMs with rare metals, including the preparation methods, compositional classifications, electromagnetic loss mechanisms, and, particularly, multiscale performance optimization strategies such as nanoscale heteroatom doping and high‐entropy design, microscale conductive phase incorporation and matrix design, and milliscale double‐layer gradient structures and metamaterial engineering. Although significant progress has been achieved, challenges remain in the following sectors: ultra‐high‐temperature stability (> 1273 K), extremely‐thin absorption (< 1 mm), multispectral stealth, characterization techniques, and engineering reliability. Future directions should emphasize matrix/morphology engineering, wide‐temperature adaptation, ultra‐thin design, multifunctional integration, characterization innovation, and reliability validation, providing a roadmap for next‐generation HTMAMs with rare metals.
