Eur. Phys. J. B 66, 483-487 (2008)
https://doi.org/10.1140/epjb/e2008-00461-9

Electronic structure, ferroelectricity and optical properties of CaBi₂Ta₂O₉

¹ Department of Mathematics and Information Sciences, North China Institute of Water Conservancy and Hydroelectric Power, 450008, Zhengzhou, P.R. China
² College of Physics and Information Engineering, Henan Normal University, 453007, Xinxiang, P.R. China
³ Department of Physics, Huazhong University of Science and Technology, 430074, Wuhan, P.R. China

Corresponding author: ^a hnsqxubin@163.com

Received: 22 October 2008
Published online: 18 December 2008

Abstract

Using first-principles calculations based on density-functional theory in its local-density approximation, we investigated the Electronic structure, ferroelectricity and optical properties of CaBi₂Ta₂O₉ (CBT) for the first time. It is found that CBT compound has an indirect band gap of 3.114 eV and the O 2s and 2p states are strongly hybridized with the 6s states of Bi which belong to the (Bi₂O₂)²⁺ planes. The quite strong Ta–O and Bi–O hybridization is the primary source for ferroelectricity. Our results imply that the interaction between Bi and O is highly covalent. The anisotropy occurs mainly above 4 eV in the optical properties. The different optical properties have been discussed.