Ab initio study of $Li_2CaTa_2O_7$ compound: electronic and optical properties for three phases

Özet

The $Li_2CaTa_2O_7$ compound belongs to the Ruddlesden–Popper family of layered perovskites. First principleapproximation was used to investigate the electronic band structure and optical properties of the compound for threephases. Independent of the studied compound’s structural type, $Li_2CaTa_2O_7$ has semiconductor behavior and directtransition. 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 opticalresponse of the chosen axes of the compound to incoming electromagnetic rays varies with phase transition.