Morphology Regulation and Defect Engineering of Ni-Doped LaMnO3 Nanostructured Perovskites toward High-Performance Microwave Absorption

Perovskite oxides with excellent structural compatibility and tunable electronic structures are ideal high-performance electromagnetic wave absorbers. Conventionally ion-modified LaMnO3 perovskites usually exhibit a single loss modulation mode. Few studies have discussed the shift rule of effective absorption bands under different doping ratios. Meanwhile, systematic research combining low-valent metal doping with microstructure regulation is still scarce. Herein, a series of nanoscale LaMn1−xNixO3 (0 ≤ x ≤ 0.25) perovskites were synthesized via the sol−gel method. Non-equivalent Ni2+ doping induces multivalent Mn coexistence, regulates oxygen vacancies, and triggers lattice distortion to jointly optimize conductive loss and polarization loss. Ni doping drives the formation of an interconnected network architecture composed of particle-assembled rod-like structures, which boosts electromagnetic multi-scattering and interfacial polarization. The optimized sample delivers excellent microwave absorption performance with a minimum reflection loss of −54.52 dB and an effective absorption bandwidth of 4.7 GHz, achieving frequency-tunable absorption over the C, X, and Ku bands.