Abstract
Ferromagnetic composites which contained. iron and iron zinc ferrite(ZnxFe3-xO4) were prepared by the Thermite method, and their crystal phases and magnetic properties were investigated. The mixtures of Zn/α-Fe2O3 molar ratio of 0.3-2.0 were sintered between 400°C and 800°C for 1 hr in argon gas, and then were quenched.
The samples that were sintered between 450°C and 500°C had a large amount of a spinel phase(ZnxFe3-xO4). When the samples were sintered between 550°C and 700°C, the spinel phase was decreased by the thermal decomposition: non magnetic oxides, FeO and ZnO were formed. Iron powders were formed by the sintering at 800°C or above. The spinel phase was formed when Zn/α-Fe2O3 with molar ratio less than 1 was sintered at 500°C for 1hr in argon gas. The sample whose molar ratio of 0.35 had the magnetization of 85 emu/g and the coercive force of 0.11 kOe. The synthesized fine particles were sperical in shape and their diameters were in the range of 0.3 to 0.6μm. The future work is to make ferromagnetic materials which coexist irons and spinel ferrites without non magnetic oxides.
