Vacancy-mediated electromagnetic loss tuning in Cr-doped lanthanum manganite perovskites for broadband and high-intensity microwave absorption

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 O₃) 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.