High-power-use Mn–Zn ferrites with monodomain structure prepared by low-temperature sintering

Abstract

Densely sintered Mn–Zn ferrites with grain size varying between 1 and 6 μm were obtained. Then the effect of grain size was investigated in detail by power loss analysis and scanning electron microscopy examination of microstructure. It is found that the power loss is seen to be lowered from 260 to 120 kW/m3 at 500 kHz, 50 m T and 90 °C with grain size decreased in the order of 3 μm. It is assumed that the residual loss from domain wall resonance is a dominant factor of power loss from 500 kHz to 1 MHz. Therefore we conclude that Mn–Zn ferrite display a grain size dependent power loss with transition at grain size about 3 μm due to the absence of intragranular domain wall and these fine core materials can be prepared by low sintering temperature and the optimum control of atmosphere containing 0.5% O2.