Srフェライト焼結体の組織と保磁力に及ぼすCaO及びSiO_2添加の影響

概要

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Effects of CaO and SiO_2 addition on microstructure and intrinsic coercivity (iHc) of sintered Sr-ferrite were investigated. The amount of CaO and SiO_2 additives had direct effects upon microstructure and iHc. In CaO addition, remarkable grain growth parallel to the c-plane of Sr-ferrite crystals was observed, resulting in a decrease in iHC below 80 kA・m^<-1>. On the other hand, simultaneous addition of CaO and SiO_2 suppressed the grain growth of Sr-ferrite crystals and shifted the grain size distribution to smaller values. As the amount of SiO_2 additive increased, iHC increased up to 250 kA・m^<-1> in spite of the further densification with raising sintering temperature. In this case, sintered Sr-ferrite had a homogeneous microstructure consisting of nearly isodimensional crystals in the directions parallel to the c-plane and c-axis. Therefore, the increase in iHC of sintered Sr-ferrite with suitable amounts of CaO and SiO_2 can be attributed to the decrease in average size of crystals having nearly spherical geometry, which enhances shape magnetoanisotropy of Sr-ferrite crystals.
社団法人日本セラミックス協会の論文
1992-12-01