Natural Resonance Regulation of CexBa1-xCo2Fe16O27 Hexaferrite via In Situ Doping Strategy for Efficient Microwave Absorption

Recently, hexagonal ferrites (hexaferrites) have attracted increasing attention for high-performance microwave absorption owing to their favorable magnetic and dielectric properties. However, their natural resonance in the GHz region limits their application in narrow-band high-frequency absorbers. Herein, Ce3+-doped BaCo2Fe16O27(CBCF) hexagonal ferrite sheets with varying Ce concentrations were successfully synthesized via a sol–gel method combined with high-temperature calcination. With increasing Ce3+ content, the diffraction peaks shifted towards higher angles, and the magnetic parameters of the W-type hexaferrite were effectively improved. The saturation magnetization increased from 75.66 to 83.73 emu/g. Notably, the Ce0.075Ba0.925Co2Fe16O27(C0.075BCF) sample exhibited excellent broadband absorption performance, achieving a minimum reflection loss (RL) of −18.40 dB at 14.92 GHz and an effective absorption bandwidth of 5.52 GHz. The microwave absorption performance was effectively controlled by tuning the natural resonance frequency of the W-type hexaferrite via Ce doping. This study provides a new strategy for designing broadband microwave absorbers by modulating the natural resonance frequency.