First principles study on lattice vibration and electrical properties of layered perovskite Sr_2M_2O_7(M=Nb, Ta)

作     者：Xing Liu Hui-Qing Fan 刘星;樊慧庆

作者机构：State Key Laboratory of Solidification ProcessingSchool of Materials Science and Engineering Northwestern Polytechnical University.Xi＇an 710072 China 

出 版 物：《Chinese Physics B》 (中国物理B（英文版）)

年 卷 期：2018年第27卷第8期

页      面：406-414页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：Project supported by the National Natural Science Foundation of China(Grant No.51672220) the 111 Program of the Ministry of Education of China(Grant No.B08040) the National Defense Science Foundation(Grant No.32102060303) the Xi’an Science and Technology Foundation the Shaanxi Provincial Science Foundation the Gaofeng Project of Northwestern Polytechnical University,China(Grant No.17GH020824) 

主　　题：Sr2M2O7, first-principles dielectric and piezoelectric properties Born effective charge sponta-neous polarization 

摘      要：In this paper, we performed calculations to investigate the dielectric, piezoelectric properties, Born effective charge （BEC）, and spontaneous polarization of Sr2M207, the method used in our study was a well-known density functional theory based on first-principles. The optimized results were in good agreement with previous experiments and calculations. which indicates that our calculated method is reasonable. The research we have done suggested that greater piezoelectric components of Sr2Nb207 were e31 and e33, and the contributions were derived from the A I. By studying the Born effective charge, it could be seen that the valence of ions changed, and the O of Sr2Nb207 were most obviously that caused by the covalent character of ions and the hybridization of O-2p and Nb-4d. The spontaneous polarization of Sr2Nb2O7 in the [001 ] direction is 25 p_C/cm2, while for Sr2Ta2O7, there was no spontaneous polarization in the paraelectric state. Finally, the effect of pressure on the piezoelectric properties were also investigated, the polarization of Sr2Nb2O7 decreased linearly with the increase alter pressure. All our preliminary results throw light on the nature of dielectric, piezoelectric properties, Born effective charge, and spontaneous polarization of Sr2M2OT, it was helpful for experimental research, the development of new materials, and future applications.