Ab initio study of Li2 CaTa2O7 compound: electronic and optical properties for three phases.

The Li₂CaTa₂O₇ compound belongs to the Ruddlesden-Popper family of layered perovskites. First principle approximation was used to investigate the electronic band structure and optical properties of the compound for three phases. Independent of the studied compound's structural type, Li₂CaTa₂O₇ has semiconductor behavior and direct transition. In addition, the forbidden energy band gap of the compound decreases with rising temperature, as expected. Furthermore, the 3d orbital of Ca contributes to the conduction band due to the crystal field effect. Moreover, the optical response of the chosen axes of the compound to incoming electromagnetic rays varies with phase transition. [ABSTRACT FROM AUTHOR]