CaO segregation in MnZn ferrite

The reaction between CaO and MnZn ferrite is investigated by in-situ heating in a scanning electron microscope. The existence of an intermediate phase and a eutectic liquid at about 1300°C is observed. The CaO segregation behavior of low loss MnZn ferrite is studied by in-situ heating in transmission electron microscope and Auger electron spectroscopy. The Ca is observed to stay at the grain boundaries in the form of amorphous intermediate phase at low temperatures and in a liquid phase at the sintering temperature.