Optimizing the Soft Magnetic Properties of Mn-Zn Ferrite by a Proper Control of Sintering Process

Manganese zinc (Mn-Zn) ferrites were prepared by solid-state reaction. The sintering process was investigated in detail using differential scanning calorimetry/thermogravimetric analysis and x-ray diffraction characterizations. A three-step weight loss was observed and the main Mn-Zn ferrite formation reaction was detected. Two-step heat treatment was employed to achieve high density Mn-Zn ferrite. For sintering temperatures from 1300 degrees C to 1400 degrees C, crystal grains of Mn-Zn ferrite became uniform with larger size and more equiaxed shape. The grain boundaries changed from curved to straight. Such features were believed helpful for the magnetic domain wall movement. In addition, better diffusivity at higher sintering temperature homogenized the distribution of impurities which also facilitated the magnetic domain alignment. Thanks to the microstructure acquired by controlling the sintering process, a high-amplitude permeability of 1151, a low total loss of 411 W/kg and coercivity of 57.63 A/m at 65 kHz were simultaneously achieved on samples sintered at 1400 degrees C.