抄録
Single phase Sr-Pr-Co 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, PrCl3 · 7H2O and CoCl2 · 6H2O. The chemical coprecipitation composition were chosen according to the formula {(SrO) · n/2(Fe2O3)}100-x-y(Pr2O3)x(CoO)y, where n was fixed at 7.0, x was varied between 1.0 and 12.0, y between 2.0 and 10.0. A water solution containing Sr2+, Fe3+, Pr3+ and Co2+ was poured into a solution of NaOH (pH=13.0).
The precipitated products were boiled at 100°C for 2 h, and they were carefully washed with pure water for 24 h. The washing was repeated 5 times and the products were then filtered and dried at 80°C for 12 h. The obtained fine particles were heated at a temperature between 950 and 1100°C for 2 h in air to get single phase Sr-Pr-Co M-type ferrite fine particles. The most prominent magnetic properties have been observed for the sample with the preparation composition of {(SrO) · 3.5(Fe2O3)}89.0(Pr2O3)5.0(CoO)6.0; they are as follows: σs=84.0×10-6 Wb · m/kg (66.8 emu/g), σr=43.7×10-6 Wb · m/kg (34.7 emu/g), HcJ=528.8 kA/m (6.65 kOe), α (σr)=-0.18 %/°C, α (HcJ)=0.07 %/°C and Tc=459°C.
