Effects of Second Milling Time on Temperature Dependence and Improved Steinmetz Parameters of Low Loss MnZn Power Ferrites

Low loss MnZn power ferrites with different second milling times were prepared via the conventional ceramic process. The microstructures, magnetic properties, temperature dependence, and improved Steinmetz parameters of the sintered ceramics have been analyzed. The results show that properly increasing second milling time can remarkably increase the magnetic properties and temperature dependence. When the second milling time is two hours, the initial permeability and saturation magnetic induction reach their maximum, while the total power loss achieves its minimum value, which is lower than 430 kW/m³ at wide temperature range (25 °C ~ 120 °C). The improved Steinmetz parameters reveal that the absolute value of ct₀, ct₁ and ct₂ of all samples present decreasing trends along with the increasing of frequency. Moreover, the minimum power loss temperature moves to a lower temperature, the total effect of temperature on power loss becomes smaller, and the temperature stability of low loss MnZn power ferrites becomes better.