Low temperature sintered MnZn ferrites for power applications at the frequency of 1 MHz

Abstract The low power loss Mn-Zn ferrites with fine grains were developed by the low-temperature-sintering ceramic process for power applications at a high frequency of 1 MHz. The LiBO2 sintering aid was added to promote the low temperature sintering and densification. The effects of LiBO2 on micromorphology and magnetic properties of the sintered Mn-Zn ferrites were investigated. With the aid of LiBO2, sintering temperature could be reduced as low as 990 ℃. The optimum sample was obtained by the addition of 500 ppm LiBO2 sintered at 1020 ℃. The average grain size of this sample is 2.78 μm, the density reaches 4.82 g/cm3, and the minimum power loss is 310 kW/m3 at 1 MHz/30 m T and 25 ℃. This sample shows good wide-temperature stability of power loss. The mechanism of power loss affected by the LiBO2 addition was also discussed. The ceramic sintering process combining the low temperature sintering and the sintering aid offers a new way to develop high-frequency Mn-Zn ferrites.