Synthesis of Ni-Zn ferrite and its microstructure and magnetic properties

Abstract

Nanometer Ni_0.5Zn_0.5Fe₂O₄ powders with spinel phase were prepared by the hydrothermal method using purified FeSO₄ solution from sodium jarosite’s slag as materials. The results show that the spinel phase of Ni_0.5Zn_0.5Fe₂O₄ powders begins to form at a relatively low temperature (130 °C) and a shorter holding time (1 h) when pH=8. The crystallization kinetics equation at 200 °C is ln[-ln(1−x)] = −0.78+0.95ln t. The growth activation energy of Ni_0.5Zn_0.5Fe₂O₄ grains is 41.6 kJ/moL in hydrothermal synthesis process. With the increase of sintering temperature, the density and diameter shrinkage of ferrite circulus increase, whereas its pores decrease. The results of magnetic measurements show that saturation magnetic flux density B_s increases and the coercivity H_c decreases with the increase of their sintering temperature. Magnetic parameters of all the investigated samples satisfy the character demand of high B_s, low B_r and low H_c of soft magnetic ferrite materials.

Keywords

sodium jarosite / hydrothermal synthesis / Ni-Zn ferrite / nanoparticle

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