First-principles calculation of temperature-dependent electronic transitions mechanism in V or Nb substituted BiFeO3 |
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Authors: | Hai-long Li Liang Bian Fa-qin Dong Mian-xin Song Wei-min Li Frank S. Riehle Xiao-qiang Jiang Yan-hui Lin Cheng-xia Wang Yu Li Wei-hui Luo |
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Affiliation: | Key Laboratory of Solid Waste Treatment and Resource Recycle, Southwest University of Science and Technology, Mianyang, Sichuan, China |
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Abstract: | Here, we present a simulation study of temperature-dependent electronic transitions in BiVO3 (BVO) and BiNbO3 (BNO) using density functional theory (DFT) together with generalized gradient approximation (GGA) and two-dimensional correlation analysis (2D-CA). The results indicate that heat accumulation can accelerate the degeneracy of V-3d orbital in BVO and the splitting of Nb-4d orbital in BNO at 750 K. We found changes in the type of d–p hybrid orbital as follows, for BVO: V-dx2+y2 + dZ2-O-2pz → V-dx2+y2-O-2pz; and for BNO: Nb-dx2+y2-O-2pz → Nb-dx2+y2 + dZ2-O-2pz. Furthermore, we found changes in the type of hybrid orbital leading to the following electron–electron interactions, for BVO: t2g (V-dZ2-O-2pz) + eg (V-dx2+y2-O-2pz) → t2g (V-dx2+y2-O-2pz); and for BNO: t2g + eg (Nb-dx2+y2 + dZ2-O-2pz) → t2g (Nb-dx2+y2-O-2pz) + eg (Nb-dz2-O-2pz). The electronic transitions are determined by a charge-transfer from the occupied O-2p4 orbitals to the unoccupied V-3d3 (or Nb-4d3) and Bi-6p3 orbitals. Due to the temperature-dependent electronic structure closely related to these electronic transitions, this study provides a new perspective for the design and improvement of BFO-based temperature-sensitive devices. |
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Keywords: | 2D-CA technique DFT electronic transitions orbital hybridization |
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