산소 결핍에 따른 Fe가 도핑된 TiO2-δ의 상온 강자성 현상에 관한 연구

Abstract

Effects of oxygen deficiency on the room temperature ferromagnetism in Fe-doped reduced TiO2 have been investigated by comparing the air-annealed Ti0.97Fe0.03O2 compound with secondly post-annealed one in vacuum ambience. The air-annealed sample showed a paramagnetic behavior at room temperature. However, when the sample was further annealed in vacuum, a strongly enhanced ferromagnetic behavior was observed at same temperature. M ssbauer spectra of air-annealed sample at 295K showed a single doublet of Fe3+, suggesting that the Fe ions are paramagnetic. On the other hand, the absorption spectra after vacuum-annealing exhibited two doublets, in which one is the same component with air-annealed sample and the other is new doublet corresponding to Fe2+ state. This result suggests that the occurrence of ferromagnetism in reduced sample may be interpreted as the contribution of unquenched orbital moment of Fe2+ ions.