Effect of metal-oxygen covalent bonding on the competition between Jahn-Teller distortion and charge disproportionation in the perovskites of high-spin d(4) metal ions LaMnO(3) and CaFeO(3)

Inorganic Chemistry
M H WhangboM Pouchard

Abstract

The perovskites LaMnO(3) and CaFeO(3) consisting of high-spin d(4) transition metal ions undergo different types of distortions, i.e., a Jahn-Teller distortion in LaMnO(3) and a charge disproportionation in CaFeO(3). We investigated the electronic factor causing this difference on the basis of first principles spin-polarized electronic band structure calculations for their ideal cubic structures and also tight-binding electronic band structure calculations for their ideal cubic and distorted structures. Our study shows that a charge disproportionation is favored over a Jahn-Teller distortion in CaFeO(3) because the covalent character is strong in the Fe-O bond, while the opposite is true for LaMnO(3) because the covalent character is weak in the Mn-O bond. In spin-polarized electronic band structure calculations, the covalency of the M-O (M = Fe, Mn) bond is enhanced in the up-spin bands but is reduced in the down-spin bands. Our analysis shows that electron-electron repulsion causes the energy gap between the metal 3d and the oxygen 2p orbitals to become larger for the down-spin than for the up-spin-orbital interactions. Thus in the d-block e(g) bands of both LaMnO(3) and CaFeO(3) the metal 3d orbital contribution is larger in...Continue Reading

References

Jan 15, 1996·Physical Review. B, Condensed Matter·W E Pickett, D J Singh
Dec 2, 1991·Physical Review Letters·M TakanoJ B Goodenough
Oct 28, 1996·Physical Review Letters·J P PerdewM Ernzerhof

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Citations

Sep 23, 2014·The Journal of Chemical Physics·Antonio Cammarata, James M Rondinelli
Oct 24, 2012·Journal of the American Chemical Society·Toshihiro TakashimaRyuhei Nakamura
May 4, 2017·Chemical Communications : Chem Comm·Hideshi OokaRyuhei Nakamura

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