Double‐Exchange Effect and Defects Synergy in High‐Entropy Perovskites for Multispectral Electromagnetic Response

Non‐equimolar designs have greatly expanded the development space in high‐entropy perovskites (HEPs) as electromagnetic wave absorption (EMA) materials. Among them, the relationship between the variation of component contents and the performance of EMA is the key to the precise design of components, but it is rarely reported. In this study, a low‐valent ions concentration gradient is established to regulate the concentration of oxygen vacancies (Ovs), the degree of lattice distortion, and the intensity of the double‐exchange effect, thereby controlling the relaxation loss and conductivity loss, and effectively improving the EMA performance of HEPs. Herein, (Sr 0.2 La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 )FeO 3 achieves the effective absorption bandwidth (EAB) of 5.09 GHz at a thickness of only 1.6 mm, with the minimum reflection loss ( RL min ) of −39.59 dB at 1.46 mm. Additionally, the simulation results show that it has a promising application prospect as an EMA coating and wireless communication system. Finally, the excellent electromagnetic response characteristics of HEPs in the infrared band and their excellent corrosion resistance in the seawater environment are emphasized, highlighting the great potential of HEPs as a multifunctional EMA material.