Crystal orientation and magnetic properties of Mn-Zn ferrites made use of acicular α-FeOOH

摘要

Crystal oriented manganese zinc ferrites were made from acicularα-FeOOH, Mn(C{sub}5H{sub}7O{sub}2){sub}3 and Zn(C{sub}5H{sub}7O{sub}2){sub}2 as raw materials. The materials were mixed and calcined at 800°C for 4 hours in nitrogen atmosphere. Thecalcined acicular manganese zinc ferrite fine particles were formed into a thin troidal cores, consist of multi-layered. The green bod'ies were sintered at the range of 1100 to 1250°C for 4 to 8 hours in air, thereafter cooled in nitrogen atmosphere.The crystals of sintered manganese zinc ferrites were strongly oriented to the direction of {111} plane of the spinel, which was all formed along the upper plane of troidal cores. The behavior of crystal growth was similar to that of manganese zincferrite single crystal. The initial permeability of crystal oriented manganese zinc ferrites was 1380 at 0.1 MHz and it was not allowed to decay up to 2.2 MHz at the operating condition of the 3dB decrease of the initial permeability. The high crystalorientation and suitable grain size has greatly contributed to the improvement of magnetic properties.