The effect of V2O5 addition on the microstructure and magnetic properties of Mn-Zn ferrites

In response to the need for the improvement of low-loss core materials used for high-frequency power transformers, microstructures and magnetic properties of Mn-Zn ferrite have been investigated with the addition of CaO, SiO2 adn V2O5. The specimens of (Mn0.72Zn0.22O)(0.94)(Fe2O3)(1.06) composition are prepared from the powders synthesized by SHS (Self-propagation High-temperature Synthesis) process. The presence of V2O5 in the addition to the CaO and SiO2 results in a fine grain structure and suppress the abnormal grain growth. The electrical resistivity increases with the addition of V2O5, which is believed to be attributed to the melting of V2O5 and formation of liquid phase at grain boundaries. The eddy-current loss is, therefore, lowered with addition of V2O5. However, if V2O5 is over-weighted above an optimum value, the hysteresis loss becomes dominant and, therefore, the total core-loss increases.