The Effect of Sintering Conditions on the Power Loss Characteristics of Mn-Zn Ferrites for High Frequency Applications

The sintering temperature significantly changed the microstructure and effected the power loss behavior at the frequency range over 100kHz. The best power loss characteristics at l00kHz-200mT and 500kHz-50mT were observed in the samples sintered at 1300°C and 1250°C, respectively. Those results indicated that the power loss depended on the grain size, electrical resistivity and density of sintered cores. To maintain the stoichiometry at the sintering condition, the ferrite cores were processed on the isocomposition lines within the spinel phase boundary when being cooled. The zinc vapor pressure as well as the oxygen partial pressure was controlled. The high zinc loss condition had an adverse effect on the microstructure of the sintered core surface and degraded the power loss characteristics.