Grain refinement and high-frequency properties of spark plasma sintered MnZn ferrite

Abstract

MnZn soft magnetic ferrites are essential materials for energy conversion in power electronics. The rapid development of miniaturized and energy-saving electronics has put forth an urgent need for high-frequency MnZn ferrites. However, the current MnZn ferrites suffer from a rapid decline of permeability and a drastic increase in power loss at frequencies above 5 MHz, which severely limits their use in high-frequency power electronics. In this study, the Spark Plasma Sintering (SPS) technology was used to prepare high-frequency MnZn ferrites. Compared to samples prepared by traditional solid-state sintering, SPS ferrite exhibits superior high-frequency properties with cut-off frequency of 57 MHz, and a power loss of 169.6 kW/m3 at 20 MHz. The improved high-frequency performance is due to the monodomain structure which is induced by grain refinement via spark plasma sintering. This study presents an effective method for manufacturing high-frequency soft magnetic ferrite and will promote the development of high-performance power electronics.