High temperature stability of Co-doped MnZn ferrites for automobiles

High temperature stability on core loss of Co-doped MnZn ferrite was investigated. It is confirmed that addition of Ti to Co-doped MnZn ferrite increased high temperature stability of core loss remarkably. By addition of Ti, degradation degree of core loss in a temperature range from 25°C to 150°C is less than 5% during high temperature storage test at 150°C for 2000 hours. According to the relationship between cation vacancy and degradation degree, the Ti-doped materials show low degradation degree even in present of much cation vacancy. The activation energy of cation diffusion was estimated from the degradation degree of core loss, the activation energy of Ti-doped material increased by approximately 10%, compared with only Co-doped material. As a result, an excellent ferrite material with both low loss and high temperature stability of core loss suitable for automobile was developed. © 2014, Journal of the Japan Society of Powder and Powder Metallurgy. All rights reserved.