Germanium Antimony Bonding in Ba4Ge2Sb2Te10 with Low Thermal Conductivity

Jana, Subhendu and Panigrahi, Gopabandhu and Ishtiyak, Mohd and Narayanswamy, Sake and Bhattacharjee, Pinaki Prasad and Niranjan, Manish K. and Prakash, J. (2022) Germanium Antimony Bonding in Ba4Ge2Sb2Te10 with Low Thermal Conductivity. Inorganic Chemistry, 61 (2). pp. 968-981. ISSN 0020-1669

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Abstract

A new quaternary telluride, Ba4Ge2Sb2Te10, was synthesized at high temperature via the reaction of elements. A single-crystal X-ray diffraction study shows that the title compound crystallizes in its own structure type in the monoclinic P21/c space group having cell dimensions of a = 13.984(3) A, b = 13.472(3) A, c = 13.569(3) A, and β = 90.16(3)° with four formula units per unit cell (Z = 4). The pseudo-one-dimensional crystal structure of Ba4Ge2Sb2Te10 consists of infinite 1∞[Ge2Sb2Te10]8- stripes, which are separated by Ba2+ cations. Each of the Ge(1) atoms is covalently bonded to four Te atoms, whereas the Ge(2) atom is covalently bonded with one Sb(2) and three Te atoms in a distorted tetrahedral geometry. The title compound is the first example of a chalcogenide that shows Ge-Sb bonding. The Sb(1) atom is present at the center of the seesaw geometry of four Te atoms. In contrast, the Sb(2) atom forms a seesaw geometry by coordinating with one Ge(2) and three Te atoms. Condensation of these Ge and Sb centered polyhedral units lead to the formation of 1∞ [Ge2Sb2Te10]8- stripes. The temperature-dependent resistivity study suggests the semimetallic/degenerate semiconducting nature of polycrystalline Ba4Ge2Sb2Te10. The positive sign of Seebeck coefficient values indicates that the predominant charge carriers are holes in Ba4Ge2Sb2Te10. An extremely low lattice thermal conductivity of ∼0.34 W/mK at 773 K was observed for polycrystalline Ba4Ge2Sb2Te10, which is presumably due to the lattice anharmonicity induced by the stereochemically active 5s2 lone pair of Sb. The electronic structure of Ba4Ge2Sb2Te10 and the bonding of atom pairs in the structure have been analyzed by means of ELF analysis and crystal orbital Hamilton population (COHP) analysis. ©

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IITH Creators:

IITH Creators	ORCiD
Bhattacharjee, Pinaki Prasad	http://orcid.org/0000-0002-6422-2601
Niranjan, Manish K	https://orcid.org/0000-0002-4417-5107
Prakash, J.	https://orcid.org/0000-0002-4078-9662

Item Type:

Article

Additional Information:

J.P. gratefully acknowledges the Science and Engineering Research Board (SERB), Department of Science and Technology (DST), India for the financial support under the early career research (ECR) award (Grant number: ECR/2017/000822). S.J. and G.P. thank MOE & IIT Hyderabad for the research fellowships. M.I. acknowledges the research fellowship support received by the DST-SERB (grant number: ECR/2017/000822). We thank DST-FIST(SR/FST/PSI-215/2016) for computational resources and DST-FIST (SR/FST/ETI-421/2016) for the SEM-EDX facility used in this work.

Uncontrolled Keywords:

C-space; Covalently bonded; Highest temperature; Low thermal conductivity; Monoclinics; Polycrystalline; Single-crystal X-ray diffraction studies; Structure type; Synthesised; Title compounds

Subjects:

Others > Metallurgy Metallurgical Engineering
Physics
Chemistry
Materials Engineering > Materials engineering

Divisions:

Department of Chemistry
Department of Material Science Engineering
Department of Physics

Depositing User:

. LibTrainee 2021

Date Deposited:

14 Jul 2022 13:01

Last Modified:

14 Jul 2022 13:01

URI:

http://raiithold.iith.ac.in/id/eprint/9707