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http://dx.doi.org/10.4150/KPMI.2006.13.6.401

Room-temperature Ferromagnetism in Fe-doped Reduced TiO2-δ  

Lee, H.M. (Nuclear Nanomaterials Development Lab., Korea Atomic Energy Research Institute)
Kim, C.S. (Department of Physics, Kookmin University)
Uhm, Y.R. (Nuclear Nanomaterials Development Lab., Korea Atomic Energy Research Institute)
Rhee, C.K. (Nuclear Nanomaterials Development Lab., Korea Atomic Energy Research Institute)
Publication Information
Journal of Powder Materials / v.13, no.6, 2006 , pp. 401-407 More about this Journal
Abstract
Effects of oxygen deficiency on the room temperature ferromagnetism in Fe-doped reduced $TiO_2$ have been investigated by comparing the air-annealed $Ti_{0.97}Fe_{0.03}O_2$ 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. $M{\"{o}}ssbauer$ spectra of air-annealed sample at 295K showed a single doublet of $Fe^{3+}$, 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 $Fe^{2+}$ state. This result suggests that the occurrence of ferromagnetism in reduced sample may be interpreted as the contribution of unquenched orbital moment of $Fe^{2+}$ ions.
Keywords
Diluted magnetic semiconductor; $M{\"{o}}ssbauer$ spectroscopy; Oxygen deficiency; Ferromagnetism; $TiO_2$;
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