Mössbauer study of zinc-substituted strontium cobalt Z-type hexaferrite

Polycrystalline powder samples of the zinc-substituted strontium cobalt Z-type hexaferrite: Sr₃Co_2-xZn_xFe₂₄O₄₁ (x = 0, 0.5, 1.0, 1.5 and 2.0) were prepared by the polymerizable complex method. Their Mössbauer spectra were measured at room temperature with conventional constant-acceleration spectrometer. Obtained Mössbauer spectra were numerically separated into six discrete components. The relationship between Mössbauer parameters and magnetic properties has been discussed. From the values of the isomer shift, it was found that the iron ion in Sr₃Co_2-xZn_xFe₂₄O₄₁ is trivalent with high spin. The value of the quadrupole splitting increased and changed the sign from negative to positive for the sample with x = 1.5. From the results mentioned above and the analysis of the complex permeability spectra, the magnetocrystalline anisotropy of Sr₃Co_2-xZn_xFe₂₄O₄₁ is changed from c-plane to c-axis at Zn content between x = 1.0 and 1.5. The compositional dependence of the areas of each subspectra showed that Zn²⁺ ions occupy the sites with down spin at the compositional range of x = 0.0–1.0.