The point defect and electronic structure of K doped LaCo_0.9Fe_0.1O₃ perovskite with enhanced microwave absorbing ability

ABO₃ perovskites, owning unique properties, have great research prospect in electromagnetic wave absorption field. Normally, doping can significantly regulate the dielectric loss, whereas the magnetic loss can be ignored. In this work, the crystal structure and electromagnetic properties can be regulated systematically by the K, Fe co-doping for LaCoO₃ perovskites (LKCFO) under the condition of fixed F content. In addition, the obtained samples show the obvious interfacial polarization effect on accounting to the small size effect, which is conducive to the effective microwave absorption. By analyzing the evolution of the positron annihilation lifetime and the first-principles calculation of the oxygen density of states for the series of LKCFO perovskites, it is found that the charge transport characteristics will be controlled by the point defect generated by allelic doping. The point defect content decreases and then increases as the doping level rises. The prepared perovskite exhibits the lowest defect density and the largest dielectric loss capability, which indicates that the lower point defects promote electron migration and thus enhance the dielectric loss; thus, the electromagnetic wave absorption bandwidth up to 6.2 GHz is reached. In contrast, both insufficient and excessive K doping are detrimental to the enhancement of microwave absorption. Especially, the practical application value was investigated using Computer Simulation Technology (CST) simulations. The LKCFO-2 exhibits the smallest RCS value (below −10 dBm²) at almost −90°– 90° with a thickness of 2 mm, providing an effective method for study excellent microwave absorption and scattering property.