Pressure dependence of electron density distribution and d-p-pi hybridization in titanate perovskite ferroelectrics

Article

关键词: PHASE-TRANSITIONS;    BATIO3;    TEMPERATURE;    PBTIO3;    ORIGIN;    SRTIO3;    POLARIZATION;    REFINEMENTS;    DIFFRACTION;    POPULATION;   

DOI  :  10.1103/PhysRevB.97.144109

来源: SCIE

【 摘 要 】

Electron density distributions of PbTiO3, BaTiO3, and SrTiO3 were determined by synchrotron x-ray powder diffraction up to 55 GPa at 300 K and ab initio quantum chemical molecular orbital (MO) calculations, together with a combination of maximum entropy method calculations. The intensity profiles of Bragg peaks reveal split atoms in both ferroelectric PbTiO3 and BaTiO3, reflecting the two possible positions occupied by the Ti atom. The experimentally obtained atomic structure factor was used for the determination of the deformation in electron density and the d-p-pi hybridization between d(xz) (and d(yz)) of Ti and p(x) (and p(y)) of O in the Ti-O bond. Ab initio MO calculations proved the change of the molecular orbital coupling and of Mulliken charges with a structure transformation. The Mulliken charge of Ti in the TiO6 octahedron increased in the ionicity with increasing pressure in the cubic phase. The bonding nature is changed with a decrease in the hybridization of the Ti-O bond and the localization of the electron density with increasing pressure. The hybridization decreases with pressure and disappears in the cubic paraelectric phase, which has a much more localized electron density distribution.

【 授权许可】

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