化学的共沈法によるSr-Ca-Nd系M型フェライト微粒子の磁気特性

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Single phase Sr-Ca-Nd M-type ferrite fine particles were prepared by controlling the chemical coprecipitation method and subsequent heat treatment. The chemical reagents used for this experiment were SrCl2·6H2O, FeCl3·6H2O, CaCl2·2H2O and NdCl3·6H2O. The chemical coprecipitation composition were chosen according to the formula {(SrO)1-x(CaO)x·n/2(Fe2O3)}100-y(Nd2O3)y, where n was fixed at 7.0, x was varied between 0.1 and 0.5, y between 0.0 and 8.0. A water solution containing Sr2+, Fe3+, Ca2+ and Nd3+ was poured into a solution of NaOH (pH=13.0). The precipitated products were boiled at 100°C for 2h, and they were carefully washed with pure water for 24h. The washing was repeated 5 times and the products were then filtered and dried at 80°C for 12h. The obtained fine particles were heated at a temperature between 850 and 1000°C for 2h in air to get single phase Sr-Ca-Nd M-type ferrite fine particles. The most prominent magnetic properties have been observed for the sample with the preparation composition of {(SrO)0.7(CaO)0.3·3.5(Fe2O3)}97(Nd2O3)3; they are as follows: σs=84.1×10−6 Wb·m/kg (66.9 emu/g), σr=42.5×10−6 Wb·m/kg (33.8 emu/g), HcJ=505.3 kA/m (6.35 kOe), α(σr)=−0.18%/°C, α(HcJ)=0.11%/°C and Tc=453°C.
社団法人粉体粉末冶金協会の論文