Abstract
Crystal oriented manganese zinc ferrites were made from acicular manganese zinc ferrite fine particles. The acicular manganese zinc ferrite fine particles were prepared by a conventional sintering method. The acicular fine particles had the size of the long axis of about 4μm and the aspect ratio of about 16, respectively. To orient the acicular particles magnetically, they were pressed and formed to a shape under the magnetic field of 955kA/m by wet method. The green compact was sintered at 1250°C for 14.4ks in air, then cooled in nitrogen atmosphere. The crystal orientation of the sintered body was as strong as that of the single crystal manganese zinc ferrite. Moreover, crystal oriented manganese zinc ferrite troidal cores added with SiO2 and CaO were prepared, and then the frequency dependence of initial permeability of them were measured. The troidal core with the addition of 0.25wt%: SiO2 and 2.95wt%: CaO had the initial permeability of 1200 at 2MHz. The high value of the initial permeability may be caused by uniaxial crystal orientation and high resistivity phase formed by the additives.
