First principles study of Ca in BaTiO3 and Bi0.5Na0.5TiO3 |
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| Authors: | Ittipon Fongkaew Jiraroj T-Thienprasert |
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| Affiliation: | 1. School of Physics and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand;2. Department of Physics, Case Western Reserve University, Cleveland, OH 44106-7079, USA;3. Thailand Center of Excellence in Physics (ThEP Center), Commission on Higher Education, Bangkok 10400, Thailand;4. Faculty of Science, Department of Physics, Kasetsart University, Bangkok 10900, Thailand |
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| Abstract: | BaTiO3–Bi0.5Na0.5TiO3 is one of the promising candidates as a high-temperature relaxor with a high Curie temperature and several preferred dielectric characteristics. It has been found experimentally for a long time that adding calcium to BaTiO3–Bi0.5Na0.5TiO3 improves its temperature characteristic of the capacitance [J. Electron. Mater. 39, 2471]. In this study, Calcium (Ca) defects in perovskite BaTiO3 and Bi0.5Na0.5TiO3 have been studied based on first-principles calculations. In both BaTiO3 and Bi0.5Na0.5TiO3, our calculations showed that Ca atom energetically prefers to substitute for the cations, that is Ba, Bi, Na and Ti, depending on the growth conditions. In most cases, Ca predominantly substitutes on the A-site without providing additional electrical carriers (serve as either neutral defects or self-compensating defects). The growth conditions where Ca can be forced to substitute for B-site (with limited amount) and the conditions where Ca can be forced to serve as an acceptor are identified. Details of the local structures, formation energies and electronic properties of these Ca defects are reported. |
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| Keywords: | BaTiO3 (Bi0.5Na0.5)TiO3 perovskite oxides first-principles calculations |
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