Ferromagnetic properties of anatase Ti1−xFexO2−δ thin films

Abstract

The effects of Fe doping on the magnetic and electronic properties of reduced TiO2−δ thin films have been investigated. Anatase Ti1−xFexO2−δ films exhibit a ferromagnetic behavior at room temperature for a certain range of Fe doping. Conversion electron Mössbauer spectroscopy measurements indicate that Fe2+ and Fe3+ ions coexist in the Fe-doped films, substituting the octahedral Ti4+ sites. The contribution of possible Fe3O4 clusters to the observed ferromagnetism is not likely to happen. The Ti1−xFexO2−δ films exhibit a p-type character by Hall effect measurements but the observed ferromagnetism turns out to be independent of the hole concentration. The observed ferromagnetism in the Ti1−xFexO2−δ films can be explained in terms of a direct ferromagnetic coupling between two neighboring Fe3+ ions via an electron trapped in oxygen vacancy nearby.

The effect of milling atmospheres on photocatalytic property of Fe-doped TiO2 synthesized by mechanical alloying

“…This increase can accelerate phase transformation from anatase to rutile [22]. Similar results were also observed in the samples prepared by plasma processing and sol-gel method [23,24].…”

Structure, magnetic and optical properties of polycrystalline Co-doped TiO2 films

“…The present results are consistent with the previous reports on the (Co, Fe, Cu)-TiO 2 and Fe-HfO 2 systems [16][17][18][19], where the oxygen vacancies affect their ferromagnetism significantly. The above results show that oxygen vacancies constituted bound magnetic polarons (BMP) are the physical mechanism for the observed high-temperature ferromagnetism.…”

“…However, different results were presented by different groups, and the inconsistent results in DMSs might be due to sensitive dependence on fabrication methods and process conditions, such as substrates, temperature, oxygen pressure, etc. Recently, the physical mechanism of the high-temperature ferromagnetism in the oxide DMSs was mainly focused on the following respects: (1) oxygen vacancies, such as in the (Co, Fe, Cu)-TiO 2 and Fe-HfO 2 systems [16][17][18][19]; (2) structural defects, such as in the Cr-TiO 2 and Ni-SnO 2 systems [20][21][22][23][24], whose physical picture is not clear till now; (3) charge carriers, such as in the epitaxial Co-TiO 2 films [25,26]. In this paper, we fabricated the polycrystalline Co-doped TiO 2 films at different sputtering gas pressure using reactive facing-target sputtering.…”

Photocatalytic and Magnetic Properties of the Fe‐TiO2/SnO2 Nanofiber Via Electrospinning

“…This phenomenon was also verified by former research 15–18 . Oxygen vacancy, Ti 3+ ion, and Fe 2+ ion are all ferromagnetic defects.…”