전기폭발법에 의해 제조된 자성 Fe2O3 나노 분말의 자기적 특성연구

Abstract

Nanoparticles of Fe2O3 with a mean particle size of 4 - 30 nm have been prepared by a pulsed wire evaporation method, and its structural and magnetic properties were studied by SQUID magnetometer and Mosbauer spectroscopy. From the main peak intensity of XRD and absorption rate of Mosbauer spectrum, the amounts of γ-Fe2O3 and α-Fe2O3 in as-prepared sample are about 70% and 30%, respectively. The coercivity (53Oe) and the saturation magnetization (14 emu/g) are about 20% of those of the bulk γ-Fe2O3. The low value of coercivity and saturation magnetization indicate that the γ-Fe2O3 phase nearly shows the spin glass-like behavior. Analysis of the set of Mosbauer spectrum indicates a distribution of magnetic hyperfine fields due to the particle size distribution yielding 20 nm of average particle size. The magnetic hyperfine parameters are consistent with values reported of bulk γ-Fe2O3 and α-Fe2O3. A quadrupole line on the center of spectrum represents of superparamagnetic phase of γ-Fe2O3 with a mean particle size of 7 nm or below.