Escalating electromagnetic(EM)pollution and advanced stealth technologies require next-generation microwave absorbers that combine broadband response,strong attenuation,and lightweight characteristics with high-temper...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-x)Cr_(x)O_(3))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_(0.85)Cr_(0.15)O_(3) 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 Cr^(3+)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.展开更多
基金financial support from the Defense Industrial Technology Development Program(JCKY2023603C016).
文摘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-x)Cr_(x)O_(3))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_(0.85)Cr_(0.15)O_(3) 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 Cr^(3+)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.
