Magnetic Properties of the M-type Ferrite Fine Particles of the Ba-La-Co System Prepared by the Chemical Coprecipitation Method

Abstract

Ba-La-Co M-type ferrite fine particles were prepared by the chemical coprecipitation process and a heat treatment. The chemical reagents used for the experiment were FeCl₃⋅6H₂O, BaCl₂.6H₂O, LaCl₃⋅7H₂O, and CoCl₂.6H₂O. The chemical coprecipitation process was applied to the samples having the formula {(BaO⋅n/2(Fe₂O₃))_100-x-y(La₂O₃)_x (CoO)_y (n=7.0-12.0, x=1.0-10.0, y=1.0-10.0) the solution containing Ba²⁺, Fe³⁺, La³⁺, and Co²⁺ was poured into solution of NaOH (pH=13.0). The precipitated products were boiled for 2hs and they were carefully washed with water and dried. The obtained fine particles were heated at 950 to 1100°C for 2hs in air to obtain the single phase of Ba-La-Co M-type ferrite fine particles. The best magnetic properties were observed for the sample with the composition of {(BaO⋅n/2(Fe₂O₃))_94.0(La₂O₃)_3.0(CoO)_3.0. The maximum values of magnetic properties were as follows: σ₅=87.1×10^-6 Wb⋅m/kg(69.3 emu/g), σ_r=42.9×10^-6Wb⋅m/kg (34.1 emu/g), H_CJ=469.5 kA/m (5.82 kOe) and T_C= 456.4°C.