Vacancy-mediated electromagnetic loss tuning in Cr-doped lanthanum manganite perovskites for broadband and high-intensity microwave absorption
Shu-Qing Lv, Yanjun Jiang, Muyao Liu, Jingao Li, Zihao Zhao, Xinyu Wang, Baoshan Li, Shuo Liu, Fangzhou Cui, Dongdong Lv, Yanan Yang, Long Xia
Abstract
Escalating electromagnetic 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 electromagnetic losses in Cr-doped lanthanum manganite perovskites (LaMn<sub>1-x</sub>Cr<sub>x</sub>O<sub>3</sub>) synthesized by 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<sub>0.85</sub>Cr<sub>0.15</sub>O<sub>3</sub> achieves a remarkable minimum reflection loss of -75.37 dB and an effective absorption bandwidth of 6.0 GHz at a thickness of only 2.8 mm. Structural and spectroscopic analyses reveal that Cr<sup>3+</sup> substitution induces Mn vacancies and modulates oxygen vacancy concentrations, thereby generating defect dipoles and facilitating carrier migration. Density functional theory 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 electromagnetic compatibility applications.