Electronic Origin of Defect States in Fe-Doped LiNbO₃ Ferroelectrics

Figure 3

Proposed energy diagram resulting from the orbital interactions among Fe-3d, Nb-4d, and O-2p: (a) the schematic band structure of LN and (b) the Fe-3d states in point group 3. (c) The orbital hybridization between Fe-3d and O-2p yielding the defect states in the majority spin () band. (d) The Nb-4d and O-2p interaction leading to the O(2p)-dominant states O(2p)[Nb(4d)] in the VB and the Nb(4d)-dominant states Nb(4d)[O(2p)] in the CB. (e) The orbital interactions between Fe- and the adjacent orbitals (Nb-4d and O-2p) leading to the defect states in the minority spin () band. (f) The energy levels with an electronic configuration of the Fe²⁺(3d⁶)-related defect states: 1e²2e² in the band and 1e⁰2e⁰ in the band.