Study of Mn3O4 doping to improve the magnetic properties of MnZn ferrites

The effect of Mn3O4 doping on the magnetic properties of MnZn ferrites is studied. It is found that adding Mn3O4 as a dopant after pre-sintering, in contrast with the traditional approach of adjusting Mn3O4 content in the main composition, results in different magnetic properties of MnZn ferrites. Compared to its corresponding sample, 500 ppm Mn3O4 addtion raises the initial permeability of MnZn ferrite sample by 12.97%, and the saturated magnetic induction by 7.45%, and reduces its power loss by up to 23%. The improvement of magnetic properties will be strengthened with the increase of Mn3O4 doping amount before it reaches 0.5 wt%, continue increasing the doping amount, and the improvement will be gradually impaired. It is also found that suitable amount of Mn3O4 addition mainly reduces the hysteresis loss of MnZn ferrites at frequencies below 200 kHz, and when it is above 200 kHz, the eddy current loss can be considerably reduced. XRD and SEM data reveal that Mn3O4 doping results in no obvious change in the microstructure of MnZn ferrites. (C) 2009 Elsevier B.V. All rights reserved