Magnetic properties of Sr-M ferrite fine particles

Single phase Sr-M ferrite fine particles were prepared by the chemical coprecipitation and subsequent heat-treatment methods. The chemical reagents used for an experiment are FeCl3 . 6H(2)O and Sr(NO3)(2). A solution containing Fe3+ and Sr2+ in the molar ratio (Fe3+/Sr2+ = n) 7.0 similar to 11.0 was poured into a solution of NaOH (pH = 10 similar to 13). Aqueous suspensions containing the precipitated products were boiled for 2hs, and they were carefully washed, filtrated and dried at 80 degrees C for 8hs. The obtained fine particles were heated 800 to 1100 degrees C for 2hs in air to get single phase Sr-M ferrite fine particles. The optimum preparing condition of single phase Sr-M ferrite fine particles are as follows : reagents : FeCl3 . 6H(2)O and Sr(NO3)(2) : the molar ratio : Fe3+/Sr2+ = 8; pH = 13; the heat-treatment condition : 900 degrees C x 2hs in air. The magnetic and physical properties are sigma(s) = 87.0 x 10(4) Wb.m/kg (69.2 emu/g), H-cJ = 501.3 kA/m (6.3 kOe), H-Aave = 945.4 kA/m (11.9 kOe). Tc = 462 degrees C, the lattice constants a = 5.882 x 10(-10) m, c = 23.5 x 10(-10) m, c/a = 3.919, the activation energy = 182.0 kJ/mol (43.5 kcal/mol) and the average particle size = 0.2 mu m.