Magnetic properties on ferromagnetic FeAlO3

FeAlO3 polycrystalline sample was fabricated by the sol-gel method. The crystallographic and magnetic properties of the sample were measured using X-ray diffractometer, Mossbauer spectroscopy, and vibrating sample magnetometer (VSM). The crystal structure was found to be an orthorhombic with the space group Pna2(1), which has four cation sites labeled Fe1, Fe2, Al2(octahedral sites), and All(tetrahedral site). Magnetic hysteresis curves of FeAlO3 showed the ferromagnetic phase and a pinched-like shape at low temperature, which is similar to those of 'exchange-spring magnet'. The Curie temperature was determined to be 250 K. Mossbauer spectra were measured from 4.2 to 295 K. The isomer shifts at room temperature are 0.32 mm/s and 0.11 mm/s relative to alpha-Fe metal, which is consistent with ferric state in oxide materials. Mossbauer spectra showed line broadening and the changes in linewidth with increasing temperature, we have examined the cation distribution and anisotropy energy difference of Fe1, Fe2, Al2, and All sites. From the analysis of Mossbauer spectrum at 4.2 K, the occupancies of Fe ion on Fe1, Fe2, All, and Al2 sites are determined to be 41.15%, 38.7%, 7.8%, and 12.4%, respectively.