Escalating electromagnetic (EM) pollution and advanced stealth technologies require next-generation microwave absorbers that combine broadband response, strong attenuation, and lightweight characteristics with high-temperature stability. In this work, a vacancy-mediated strategy is proposed to tailor EM losses in Cr-doped lanthanum manganite perovskites (LaMn_1−xCr_xO₃) synthesized via a sol–gel method. The cooperative modulation between Mn-site cation vacancies and oxygen vacancies enables a well-balanced contribution of polarization loss and conduction loss, resulting in excellent absorption performance. Specifically, LaMn_0.85Cr_0.15O₃ achieves a remarkable minimum reflection loss (RL_min) of −75.37 dB and an effective absorption bandwidth (EAB) of 6.0 GHz at a thickness of only 2.8 mm. Structural and spectroscopic analyses reveal that Cr³⁺ substitution induces Mn vacancies and modulates oxygen vacancy concentrations, thereby generating defect dipoles and facilitating carrier migration. Density functional theory (DFT) calculations further elucidate the role of Cr-induced defect states in enhancing conduction and polarization losses. This vacancy-engineered approach not only establishes a new paradigm for designing high-efficiency perovskite-based microwave absorbers but also offers significant potential for high-temperature EM compatibility applications.

The rapid advancement of wireless communication and the increasing demand for electromagnetic stealth have intensified the need for high-performance electromagnetic wave absorbing materials. This work introduces an innovative bio-inspired strategy for synthesizing silicon carbide nanostructures anchored on biomass-derived carbon from fig skin via a high-temperature vapor–solid deposition method. By precisely modulating the silicon-to-carbon ratio, we developed various silicon carbide morphologies—including spherical, coral-like, and linear architectures—of which the coral-like configuration (silicon-carbide-3 (SC-3)) exhibited remarkable electromagnetic wave absorption capabilities. Specifically, SC-3 achieved a minimum reflection loss of −51.27 dB at 14.1 GHz and an effective absorption bandwidth of 4.64 GHz. The enhanced absorption is attributed to the synergistic effects of interface polarization, dipole polarization, and multiple internal reflections fostered by the unique porous structure. These findings underscore the versatility of biomass-derived carbon in tailoring advanced nanostructures and pave the way for developing next-generation electromagnetic absorbers with optimized impedance matching and broadband capabilities.

This study introduces a pioneering design concept termed the “dual-feedback healing mechanism”, which investigates the relationship between oxidation products and protective coatings. Specifically, it focuses on channeling oxidation products generated at exposed cracks in the substrate to interact with the antioxidant coatings, enabling a self-repair mechanism for cracks. BN_f/SiBN was chosen as the ceramic matrix, while the Si‒O‒Al system served as the antioxidant coating. The dynamic process of obtaining Si–O–Al (SOAC) coating involving the pyrolysis of organic precursors and the dual-feedback healing mechanism were systematically investigated. These findings indicate that when the temperature surpasses 1150 °C, the exposed BN fibers at the cracks are oxidized, transforming into B₂O₃(g). Subsequently, B₂O₃(g) reacts with SiO₂, forming a SiBO mixture. The mixture effectively diminishes the viscosity of the coating, enabling it to flow and form a fresh protective layer that effectively blocks O₂ infiltration. Consequently, after oxidation at 1500 °C, the coated samples experience a mere 3% weight loss. This technology emphasizes the interconnectivity during material transformation, utilizing matrix oxidation products as a driving force for self-healing of the coating. This approach achieves intelligent-like, targeted closure of oxygen pathways, thereby pioneering a novel concept and direction for the advancement of antioxidant coatings. Consequently, this approach not only enhances our understanding of the fundamental nature of “self-healing” but also holds significant potential in the development of reparable antioxidant coatings.