フェライトの応力特性に及ぼす組成と微細構造の影響

抄録

As is known, the magnetic properties of ferrites are liable to be influenced by external stress. In this paper we describe our study of the effects of chemical composition and microstructure on the stress sensitivity of initial permeability of NiMgCuZn ferrites. When the external stress is applied to the ferrites, the reducing of the initial permeability due to the deficiency of Fe₂O₃ is observed. Furthermore, a finely dispersed grain size in microcrystalline structure is highly effective in stabilizing of initial permeability. As the compressive stress is applied parallel to the magnetic field, the maximum initial permeability of NiCuZn ferrite can be observed at 4 MPa. On the other hand, that of MgCuZn ferrite is observed at around 0 MPa. It seems possible to stabilize the initial permeability against the external stress by a further increase in composition ratio of NiO/(NiO + MgO).