The electron charge density distributions of simple perovskite oxides, PbBO3 (B = Ti, Zr and Hf), in their cubic phase are investigated by analyzing high-energy synchrotron powder diffraction data by the maximum entropy method (MEM)/Rietveld method. Clear structural differences between the antiferroelectric and ferroelectric perovskites are revealed. In the cubic phase of PbZrO3 and PbHfO3 that undergo antiferroelectric phase transitions, the Pb atom is disordered around the special Wyckoff position. The thermal motion of the O atom is anisotropic, and the charge density distributions around the O atom are extended in the directions perpendicular to the Zr(Hf)-O3 covalent bond. None of these structural characteristics are observed in the cubic phase of PbTiO3 that undergoes ferroelectric phase transition. The distinctive structural features observed in PbZrO3 and PbHfO3 should provide a clue to the mechanism of antiferroelectric phase transition.
|ジャーナル||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|出版ステータス||Published - 2004 9 1|
ASJC Scopus subject areas
- Physics and Astronomy(all)