The influence of atmosphere on hysteresis loss and eddy current loss of low loss Mn-Zn ferrites (abstract)

Abstract

The working frequency of Mn-Zn ferrites in switching power supply has been increased recently. Therefore, the manufacturing Mn-Zn ferrites with low loss at high frequency is very important. However, there were few reports concerning the core loss of Mn-Zn ferrites.1 It is beneficial to study the parameters affecting the core loss of Mn-Zn ferrites. Therefore, we studied the influence of atmosphere on the hysteresis loss (Wh) and eddy current loss (We) for different compositions in this work. Three compositions, Mn0.70Zn0.21−xFe2.09+xO4 (x=0, 0.01, 0.02), were prepared by traditional ceramic process. The sintering condition is 1385 °C for 4 h. Then, the samples are annealed at 1100 °C for 24 h in different oxygen partial pressure (0.015–1.0 vol %). Experimental results show that both We and Wh have minimum value at different oxygen partial pressure for samples with different composition. Increasing Fe content which raises the Fe++ concentration shifts the We and Wh minimum point to higher annealing oxygen partial pressure. It is mainly due to the oxidation of Fe++ and the transition of conduction mechanism, and it will be further discussed later. We can obtain the lowest core loss for using 10 and 100 kHz are samples with composition x=0 annealed in 0.07 and 0.2 vol % oxygen partial pressure, respectively. Summarily, for application to low loss at different working frequency, it is found that different optimized atmosphere should be controlled during annealing for different composition.