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Quantum chemical study of defective chromium oxide

Abstract:

Through the use of first-principles calculations based on the Density Functional Theory (DFT) within the Generalized Gradient Approximation (GGA), a study of the defective α-Cr<inf>2</inf>O<inf>3</inf> crystal has been performed. Structural, electronic and magnetic properties due to Ti, Ca and N impurities have been studied in the periodic crystalline structure. Ti-doped supercell shows that the nature of the chemical bonding in the neighbourhood of the impurity turns into more ionic one; the microstructure of the defective region displays a tendency of atomic movements away regarding the Ti imperfection. A metallic state is observed implying the ntype conductivity. Similar atomic rearrangements are found in the Ca-doped α-Cr <inf>2</inf>O<inf>3</inf> supercell. No local energy levels within the band-gap are observed in this case. In the case of N-doped crystal some atoms move towards the impurity whereas the rest of them move outwards. Presence of the N atom reduces the band-gap width of the material. Finally, there are notable changes upon the magnetic properties of doped α-Cr<inf>2</inf>O <inf>3</inf> crystals implying that chromium oxide might not act as an antiferromagnetic substance.