Electronic Origin of Defect States in Fe-Doped LiNbO₃ Ferroelectrics

Figure 7

Energy levels at the Γ point of the a↓ gap sate of Fe-3d and the CBM with respect to the VBM in the -LiNbO₃ cell calculated by the LSDA + U approach with various terms: (a) the value of Nb-4d is fixed to be 3 eV and that of Fe-3d varies and (b) the value of Fe-3d is fixed to be 4 eV and that of Nb-4d varies. The value of band gap () accords with the energy difference between the CBM and the VBM.

(a)

(b)