Sol-gel법에 의한 초미세 분말 CoFe1.9Bi0.1O₄의 결정학적 및 자기적 성질 연구

다국어 초록 (Multilingual Abstract)

Ultrafine CoFe_(1.9)Bi_(0.1)O₄ particles were fabricated by using a sol-gel method and their magnetic and structural properties were investigated with an x-ray diffractometer (XRD), a vibrating sample magnetometer (VSM), and a Mossbauer spectrometer. The result of x-ray diffraction and Mossbauer spectoscopy showed that the powders fired at and above 523 K had only cubic spinel structures. Mossbauer spectra measurements showed that the powders annealed at 523, 723, and 823 K possessed ferrimagnetic nature and paramagnetic nature due to superparamagnetism, simultaneously at room temperature and the powders annealed at and above 923 K behaved ferrimagneticaIly. In the case of the powder annealed at 923 K, the lattice constant was a_0=8.398±0.005 Å and the hyperfine fields were Hhf(A) = 479 kOe, Hhf(B) = 502 kOe. The isomer shifts indicate that the iron ions are ferric at tetrahedral[A] and octahedral sites [B], respectively. The magnetization as a function of annealing temperature increased as increasing annealing temperature. The lagest coercivity values were Hc=1368 Oe at 923 K annealing temperature. In the case of the powder annealed at 1123 K, the magnetization value was Ms=75 emu/g and this value was similler to that of CoFe₂O₄.