钛酸铅铁电体电子能带结构的第一性原理研究

First-Principles Study on the Electronic Band Structure of Ferroelectric PbTiO_3

采用第一性原理全势线性缀加平面波方法计算了铁电材料PbTiO3(PTO)的顺电相、铁电相的电子结构.计算表明PTO的顺电相是直接带隙,铁电相是间接带隙,对顺电相和铁电相的带隙起主要作用的是Ti的3d态和O的2p态,其大小分别为1.741 eV和1.877 eV.PTO由顺电相到铁电相时,有部分电荷从O转移到Pb和Ti,于是在O与Pb和Ti之间有一个更强的杂化,降低了原子间的短程排斥力,有利于铁电相的稳定.

The electronic band structures of both the ferroelectric and paraelectric of PbTiO3 （ PTO ） are calculated by using an accurate full-potential linearized augmented plane-wave method. The calculated results show that the band gaps for the paraelectric and ferroelectric phase are direct-and indirect-band gap, corresponding to the value about 1. 741 eV and 1. 877 eV,respectively. In both the paraelectric phase and ferroelectric phase of PTO ,the valence band is mainly composed of O 2p states, and the conduction band mainly consists of Ti 3d states. From the paraelectric phase to ferroelectric phase, an stronger hybridization between Pb, Ti and O because of the charge transfer from O to Pb and Ti, reduces short-range repulsion in atoms and enhances the stability of the ferroelectric structure of PTO.