The improved saturation magnetization and initial permeability in Mn–NiZn ferrites after cooling in vacuum

Abstract

The microstructure, magnetic and elastic properties of Ni0.6–xZn0.4MnxFe2O4 (x = 0–0.6) ferrites prepared by sol–gel auto-combustion method are studied. XPS results show the presence of Ni2+, Zn2+, Mn2+, Fe3+ in specimens. XRD measurements confirm that all samples annealed in 1100 °C is pure cubic spinel structure. The lattice parameter and the grain size increase with increasing Mn2+ substitution. Mn ions gradually prefer to occupy A-site in the samples as indicated by Rietveld refinement. FTIR spectra show a shift toward low wavenumber, proving that the bond length is elongated, which causes the decrease of the elastic constants. The saturation magnetization increases monotonously from 75.6 to 81.6 emu/g as x is from 0 to 0.6. In addition, due to the transition from NiZn ferrites to MnZn ferrites, the initial permeability increases monotonously from 122.5 to 545.6. Compared with annealing process in previous work, it is found that cooling in vacuum can improve the microstructure and magnetic properties. The mixed NiZnMn can be applied in high frequency.