J. Phys. IV France 07 (1997) C1-535-C1-536
Magnetic Properties of Sr-M Ferrite Fine ParticlesH. Yamamoto1, H. Kumehara1, R. Takeuchi1 and H. Nishio2
1 School of Science and Technology, Meiji University, 1-1-1 Higashimita, Tma-ku, Kawasaki 214, Japan
2 Materials Research Center, TDK Corp., 570-2 Aza-Matsugashita, Minami-hatori, Narita 286, Japan
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 · 6H2O and Sr(NO3)2. A solution containing Fe3+ and Sr2+ in the molar ratio (Fe3+/Sr2+ = 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 : FeCl3 · 6H2O and Sr(NO3)2 : the molar ratio : Fe3+/Sr2+= 8 ; pH= 13 ; the heat-treatment condition : 900°C x 2hs in air. The magnetic and physical properties are σs=87.0x10-6, HCl = 501.3 kA/m (6.3 kOe), HAave = 945.4 kA/m (11.9 kOe), Tc = 462 °C. The lattice constants a = 5.882 x 10-10 m, c = 23.05 x 10-10m. c/a=3.919, the activation energy = 182.0 kJ/mol (43.5 kcal/mol) and the average particle size = 0.2 µm.
© EDP Sciences 1997