Effect of Thickness on Microwave Absorption Properties of Ba3Co2Fe24O41 Hexaferrite

This study investigates the thickness-dependent microwave absorption performance of Ba3Co2Fe24O41 (Co2Z) hexaferrite synthesized via a conventional solid-state reaction method. Structural analysis and Rietveld refinement confirm the dominance of the Z-type phase over the Y-type phase. SEM observations show plate-like hexagonal particles, with a crystallite size of ~117.5 nm and an average grain size of ~2.56 μm. Magnetic measurements indicate soft magnetic behavior, with a saturation magnetization of 58.80 emu/g and a low coercivity of 91.73 Oe. The as-prepared Co2Z sample exhibits strong microwave absorption performance over a wide frequency range, which can be effectively tuned by adjusting the sample thickness from 1 to 6 mm. The optimal absorption intensity reaches −27.7 dB at 2.75 GHz for a thickness of 6 mm, corresponding to ~99.9% attenuation of incident electromagnetic waves. In addition, a broad effective absorption bandwidth (EAB) of 5.5 GHz is obtained at 2 mm in Ku band, while the maximum EAB of ~6.1 GHz is achieved at an optimal thickness of 2.5 mm, covering multiple frequency bands from C to Ku. The enhanced microwave absorption performance can be attributed to the synergistic effects of impedance matching, natural ferromagnetic resonance, and multiple dielectric relaxation processes. These results indicate that the Co2Z hexaferrite is a promising candidate for tunable microwave absorption applications.