Structural, Elastic, Mechanical, Electronic, and Optical Properties of a Novel Quaternary Chalcogenide Semiconductor Ba3GeTeS4

Abstract

The structural, elastic, mechanical, electronic and optical properties of Ba3GeTeS4 have been studied by pseudopotential density functional theory static calculations. The results indicated that both the lattice constant and cell volume decrease with the increase of pressure, which match well with available previous values. The pressure has a more significant influence on the b direction than the a and c direction. The obtained elastic constants reveal that Ba3GeTeS4 is mechanically stable between 0 GPa and 20 GPa. The bulk modulus, shear modulus, and Young’s modulus are evaluated by Voigt-Reuss-Hill approximations. All these elastic moduli exhibit a monotonic feature as a function of pressure. The Poisson’s ratio, and Pugh’s criterion indicate that the ductility of this quaternary Ba3GeTeS4 compound is more and more prominent with increasing applied pressure. Meanwhile, the analysis of the electronic structures reveals that the states near the valence band top are derived from Te 5p, S 3p, and Ba 6 s orbitals, and the lowest conduction band is composed of Ge 4 s and S 3p orbitals. We expect that the findings predicted the physical properties of this compound will promote future experimental studies on Ba3GeTeS4.