Alkali metal-substituted bismuth-based perovskite compounds: A DFT study
In this study, we have performed density functional theory based calculations to investigate the effect of alkali substituents M on the structure and electronic properties of (Bi0.5M0.5)TiO3 compounds with M ¼ Li, Na and K. When the ionic radius of the substituting M cation increases, the correspo...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2019
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| Subjects: | |
| Online Access: | http://repository.vnu.edu.vn/handle/VNU_123/67691 https://doi.org/10.1016/j.jsamd.2019.06.005 |
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| Institution: | Vietnam National University, Hanoi |
| Language: | English |
| Summary: | In this study, we have performed density functional theory based calculations to investigate the effect of
alkali substituents M on the structure and electronic properties of (Bi0.5M0.5)TiO3 compounds with
M ¼ Li, Na and K. When the ionic radius of the substituting M cation increases, the corresponding direct
band gap of (Bi0.5M0.5)TiO3 also increases. The same trend is found for the O-deficient Bi0.5M0.5TiO3-
d compounds, which were investigated by removing one Oxygen atom from the super cell creating an Ovacancy
in it. The presence of the O-vacancy breaks the local symmetry of the crystal structures and
generates excess electrons in the O-deficient compounds. This results in the appearance of an indirect
bandgap in Bi0.5Na0.5TiO3-d and Bi0.5K0.5TiO3-d, except for Bi0.5Li0.5TiO3-d that still exhibits a direct
bandgap. Excess electrons induce the defect states within the original bandgap of the stoichiometric
compounds and decrease the bandgap of the O-deficient compounds. In line with the electronic calculations,
effective mass calculations have provided a preliminary insight into the photocatalytic performance
of (Bi0.5M0.5)TiO3 and reveal a positive impact of K cations on the photocatalytic activity |
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