자전 연소 전구체로 합성한 나노 크기 경/연 복합페라이트의 자기 특성

Abstract

The goal of this research is the create novel magnets with no rare-earth contents, with larger energy product by comparison with currently used ferrites. For this purpose we developed nano-sized hard-type/soft-type composite ferrite in which high remanent magnetization (Mr) and high coercivity (Hc). Nano-sized Ba-ferrite, Ni-Zn ferrite and BaFe12O19/ Ni0.5Zn0.5Fe2O4 composite ferrites were prepared by sol-gel combustion method by use of glicine-nitrate and citric acid. Nanocomposite ferrites were calcined at temperature range 700-900 o C for 1h. According to the X-ray diffraction patterns and FT-IR spectra, single phase of NiZn-ferrite and Ba-ferrite were detected and hard/soft nanocomposite ferrite was indicated to the coexistence of the magnetoplumbite-structural BaFe12O19 and spinel-structural Ni0.5Zn0.5Fe2O4 that agreed with the standard JCPDS 10-0325 data. The particle size of nanocomposite turn out to be less than 120 nm. The nanocomposite ferrite shows a single-phase magnetization behavior, implying that the hard magnetic phase and soft magnetic phase were well exchange-coupled. The specific saturation magnetization (Ms) of the nanocomposite ferrite is located between hard (BaFe12O19) and soft ferrite(Ni0.5Zn0.5Fe2O4). The remanence (Mr) of nanocomposite ferrite is much higher than that of the individual BaFe12O19 and Ni0.5Zn0.5Fe2O4 ferrite, and (BH)max is increased slightly.