Influence of Sm³⁺ Substitution on Microwave Magnetic Performance of Barium Hexaferrites

Barium hexaferrites doped with Sm³⁺, Ba_1-xSm_xFe₁₂O₁₉, x = 0.0, 0.1, were prepared by the conventional ceramic technology. 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 magneto-plumbite barium ferrite without other intermediate phase. The lattice parameters of ferrites doped with Sm³⁺ decreased, indicating that the substitution of Sm³⁺ occurred on Ba²⁺ basis site and resulted in a contract of the crystal cell. The microwave electromagnetic properties of the samples were studied at the frequency range from 2 to 18 GHz. It was shown that ε' increased slightly, and the maximum of ε" appeared at higher frequency position with Sm³⁺ doping. μ" and tanμ_r were improved significantly, and the maxima were 2.3, 2.0, respectively. All the reasons were discussed using electromagnetic theory.