Structural and Magnetic Properties of Hydrothermal Spinel Ni_0.4Zn_0.6Fe₂O₄ Ferrites

Spinel ferrite powder with a nominal composition Ni_0.4Zn_0.6Fe₂O₄ was prepared by a hydrothermal method, following by sintering at 700 °C and 900 °C, respectively. The structural and magnetic properties of specimens are studied. It is found that the large particles in specimens are the agglomerates of many small nanoscale crystallites. A strengthening of chemical polarization of the internal chemical bonds is found in the powder specimen after sintering. The saturation magnetization increases from 50.1 emu/g for as-synthesized powder to 63.1 emu/g for specimen sintered at 900 °C mainly due to the weakening of spin canting, while the coercivity exhibits a slight decreasing variation with the increase of sintering temperature.

Keywords:
soft magnetic material; hydrothermal method; phase composition; microstructure; magnetic properties