Ab initio calculation on ferromagnetic reduced anatase TiO2-δ

The room-temperature ferromagnetism of reduced anatase (TiO2-delta) is studied using density functional calculation. Two kinds of point defects, titanium interstitial and oxygen vacancy (O-v), have been studied. The calculated magnetization shows that O-v is the point defect substantially related to the observed ferromagnetism. A model of the ferromagnetism is given based on the spin-polarized Ti3F+ cluster and the double exchange between the clusters. The calculated density of states supports the model and is in agreement with the donor impurity band exchange model. (c) 2008 American Institute of Physics.