Magnetic properties of Sr-La system M-type ferrite fine particles prepared by controlling the chemical coprecipitation method

Single phase Sr-La M-type ferrite fine particles were prepared by the chemical coprecipitation and subsequent heat-treatment methods. Optimum magnetic properties were achieved with materials of composition Sr0.7942+La0.1723+Fe0.3352+Fe11.743+O19, and heat-treatment of 950 degrees C x 2h in air. The magnetic and physical properties are sigma(S) = 90.5 x 10(-6) Wb . m/kg (72.0 emu/g), H-cJ = 505.3 kA/m (6.35 kOe), Tc = 454.4 degrees C, the lattice constants a = 0.5882 nm, c = 2.303nm, the activation energy = 230.9 kJ/mol (55.2 kcal/mol), and the average particle size = 0.3 mu m.