Magnetic Properties of Sr-M Ferrite Fine Particles

Abstract

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 Fecl 3 . 6 H 2 O and Sr(NO 3 )2. A solution containing Fe 3+ and Sr 2+ in the molar ratio (Fe 3+ /Sr 2+ = n)7.0∼11.0 was poured into a solution of NaOH (pH = 10∼13). Aqueous suspensions containing the precipitated products were boiled for 2hs, and they were carefully washed, filtrated and dried at 80 °c for 8hs. The obtained fine particles were heated 800 to 1100 °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: FeCl 3 . 6H 2 O and Sr(NO 3 ) 2 : the molar ratio: Fe 3+ /Si 2+ = 8; pH = 13; the heat-treatment condition: 900 °C x 2hs in air. The magnetic and physical properties are σ s = 87.0 x 10 -6 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 °C. the lattice constants a = 5.882 x 10 -10 mm, c = 23.05 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 μm.