Abstract
We report the synthesis and characterization of a new quaternary heteroanionic chalcogenide phase, Ba3GeTeS4. A single-crystal X-ray diffraction study of a yellow-colored crystal of Ba3GeTeS4 shows that the compound is stoichiometric and crystallizes in the orthorhombic Cmcm space group having cell parameters of a = 6.8583(12) Å, b = 16.207(3) Å, c = 9.6239(19) Å, with four formula units (Z = 4) per unit cell. The unit cell of the structure consists of two Ba, one Ge, one Te, and two S sites. All the crystallographically independent atoms occupy special positions. The Ba3GeTeS4 structure is made up of zero-dimensional [GeS4]4– anionic units along with Ba2+ cations, each of that is surrounded by the Te and S atoms. An optical UV–Vis absorption study on a polycrystalline sample of Ba3GeTeS4 establishes its semiconducting nature with a direct bandgap of 2.5(2) eV consistent with the yellow color of the sample. The polycrystalline Ba3GeTeS4 shows an extremely low value of thermal conductivity (∼0.46 W/mK) at 723 K. The ab-initio DFT calculations predict a high value of the thermoelectric figure of merit (zT > 1) for the hole doped-Ba3GeTeS4 sample. The crystal orbital Hamilton population (COHP) analysis shows that the Ge–S bonds are strongest in the structure, while the strengths of the Ba–S and Ba–Te interactions are similar.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
