Multifunctional LSF/YSZ composite materials enabled for extreme microwave absorption and high thermal insulation

The development of high-temperature microwave-absorbing materials that integrate thermal insulation and structural compatibility is critically important yet challenging for practical applications in extreme thermo-electro-mechanical environments. This study proposes a new material design strategy: combining perovskite oxide La 1-x Sr x FeO 3 (LSF) which exhibits high-temperature stability, conductivity, and tunable microwave loss properties, with the classic thermal barrier coating material yttria-stabilized zirconia (YSZ) known for its excellent thermophysical performance. Systematic control of Sr substitution and the LSF/YSZ ratio enables synergistic amplification of electromagnetic attenuation, thermal insulation and coefficient of thermal expansion (CTE). The optimized composite delivers an outstanding reflection loss of −40.9 dB at an ultrathin thickness of 1.1 mm, ascribed to intensified dipole polarization via Sr doping, an adequate fraction of lossy LSF phases, and interfacial polarization at abundant LSF/YSZ boundaries. Additionally, at 1000 °C, it exhibits a CTE of 10.8 × 10 −6  K −1 and a low thermal conductivity of 1.56 W/(m·K), yielding a predicted temperature drop of 220 °C across a 1.1 mm coating. These results provide important design insights and practical foundations for multifunctional microwave-absorbing materials engineered for extreme thermo-electro-mechanical environments. Future research will focus on the stability and performance evolution of composite materials under long-term high-temperature conditions.