Development of Mn-Zn ferrites with high Bs at high temperature

Magnetic properties of Mn-Zn ferrites with compositions ranging from 60 to 85 mol% Fe2O3 have been investigated. Maximum magnetic flux density (Bs) of 550 mT at 373 K was obtained in specimens with compositions of around 70 mol% Fe2O3, where Bs is a magnetic flux density at an applied magnetic field of 1 kA/m. It has been found that Bs of each specimen with the same composition changes as an amount of Fe2+ ions changes. The amount of Fe2+ ions depends on conditions of calcination and sintering and an amount of binder in pressed toroids. Hence, proper control of the calcination, sintering and the amount of binder is important to obtain high Bs in such extremely Fe2O3-rich compositions.