Single Vacancies and Vacancy Pairs in Tetragonal BaTiO₃: A First Principles Study

Abstract

The formation energies of single vacancies and vacancy pairs in the tetragonal BaTiO₃ were studied using first principles computational method. The results show that under reduction conductions, oxygen vacancies have the lowest formation energy among single vacancies. For vacancy pairs, the formation energies of the Ba-O pair are lower than that of Ti-O under most thermodynamical conditions. Calculation of the polarization for system containing Ba-O vacancy pairs shows that depending on the direction of the electric dipole of the pair, the polarization is either enhanced or decreased, which may be related to the imprint behavior of ferroelectric materials.

Keywords:

• Single vacancies
• vacancy pairs
• BaTiO₃
• first principles

Acknowledgments

The authors would like to acknowledge support from NSFC (grant No: 10702059), from the Doctoral Program of Higher Education of China, Ministry of Education (grant No: 20070530009), from the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education (grant No: 2008890), and from the China Postdoctoral Science Foundation (grant No: 20090451102). Support from the materials science and engineering postdoctoral station at Xiangtan University is also acknowledged.