First principles study on optical and thermal properties of BaTiS3

Abstract

Electronic, optical and thermal properties of hexagonal perovskite structure of BaTiS3, are studied, by means of the density functional theory (DFT) implemented on CASTEP, Material Studio, computer program. The data is optimized with generalized gradient approximation (GGA) and exchange correlation function called local density approximation (LDA), within the Broyden-Goldfarb-Shanno (BFGS) scheme of minimization and Koelling-Harmon relativistic treatment. Structure of BaTiS3, which we studied, crystallizes in the space group P63/mmc. Our results for structural, electronic and thermal properties of BaTiS3 are reported for the first time in comparison with experimental and other theoretical results wherever these are available. The electronic band structure reveals p-type semiconducting behavior and major contribution occurs from S-3p orbitals in Valence band and the conduction band is basically constructed from Ti-3d states. Reflectivity of BaTiS3 is also founded to be higher within visible and in ultraviolet region up to 25 eV, which indicates the potentiality of this material to be utilized as a jacket to elude solar heating. Coefficient of absorption spectra of BaTiS3 reveals the conducting nature of this material. The negative values of ε1(ω) is additionally observed,which is obvious indication of Drude like behavior seen in metals. Index of refraction is relatively higher within the infrared section and steadily lowered within the visible and ultraviolet frequency region. Analysis for conductivity also favors the photoconductivity with small photon energy. Thermo dynamical properties reported for the first time with Debye temperature of 1000 K.