The microwave magnetic performance of Sm³⁺ doped BaCo₂Fe₁₆O₂₇

W-type barium hexaferrites doped with Sm³⁺, Ba_1-xSm_xCo₂Fe₁₆O₂₇ (x = 0.0, 0.05, 0.1, 0.15, 0.2) were prepared by the conventional solid-state reaction. The structure and electromagnetic properties of the calcined samples were studied using powder X-ray diffraction (XRD) and network analyzer (Agilent 8722ET). All the XRD patterns showed the single phase of the magnetoplumbite barium ferrite without other intermediate phase when x ≤ 0.15. The microwave electromagnetic properties of the samples have been studied at the frequency range from 2 GHz to 18 GHz. It was shown that ε′ and ε″ increased slightly, and the maximum of ε″ shifted to low frequency position with Sm³⁺ ions doping. The μ″ and μ′ values were improved significantly when x = 0.15, and the peak value of μ″ was about 1.6 at 7 GHz and 1.75 at 18 GHz position, respectively, exhibiting excellent microwave magnetic performance. Furthermore, the reasons have also been discussed using electromagnetic theory. Ba_0.85Sm_0.15Co₂Fe₁₆O₂₇ powders (85% by weight) were mixed with epoxy resin to form compound coating materials with different thicknesses, the reflection loss values of which were also measured. It is shown that the reflection loss value increases with the increase of the coating thickness under our experimental range. The maximum of reflection loss reached about -23 dB and it was below -10 dB at the frequency range from 8 GHz to 18 GHz, when the thickness was 1.8 mm.