Ternary Chalcogenides BaMxTe2 (M = Cu, Ag): Syntheses, Modulated Crystal Structures, Optical Properties, and Electronic Calculations

Jana, Subhendu and Ishtiyak, Mohd and Panigrahi, Gopabandhu and Prakash, J. and et al, . (2020) Ternary Chalcogenides BaMxTe2 (M = Cu, Ag): Syntheses, Modulated Crystal Structures, Optical Properties, and Electronic Calculations. Inorganic Chemistry, 59 (17). 1 -10. ISSN 0020-1669

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Abstract

Standard solid-state methods produced black crystals of the compounds BaCu0.43(3)Te2 and BaAg0.77(1)Te2 at 1173 K; the crystal structures of each were established using single-crystal X-ray diffraction data. Both crystal structures are modulated. The compound BaCu0.43(3)Te2 crystallizes in the monoclinic superspace group P2(αβ1/2)0, having cell dimensions of a = 4.6406(5) Å, b = 4.6596(5) Å, c = 10.362(1) Å, β = 90.000(9)°, and Z = 2 and an incommensurate vector of q = 0.3499(6)b∗ + 0.5c*. The compound BaAg0.77(1)Te2 crystallizes in the orthorhombic P21212(α00)000 superspace group with cell dimensions of a = 4.6734(1) Å, b = 4.6468(1) Å, c = 11.1376(3) Å, and Z = 2 and an incommensurate vector of q = 0.364(2)a*. The asymmetric unit of the BaCu0.43(3)Te2 structure comprises eight crystallographically independent sites; that for BaAg0.77(1)Te2 comprises four. In these two structures, each of the M (M = Cu, Ag) atoms is connected to four Te atoms to make two-dimensional layers of [MxTe4/4]n- that are separated by layers of Ba atoms and square nets of Te. A Raman spectroscopic study at 298(2) K on a pelletized polycrystalline sample of BaAg0.8Te2 shows the presence of Ag-Te (83, 116, and 139 cm-1) and Ba-Te vibrations (667 and 732 cm-1). A UV-vis-NIR spectroscopic study on a powdered sample of BaAg0.8Te2 shows the semiconducting nature of the compound with a direct band gap of 1.0(2) eV, consistent with its black color. DFT calculations give a pseudo bandgap with a weak value of the DOS at the Fermi level. Copyright © 2020 American Chemical Society.

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IITH Creators:

IITH Creators	ORCiD
Prakash, J.	https://orcid.org/0000-0002-4078-9662

Item Type:

Article

Additional Information:

J.P. would like to thank the Science and Engineering Research Board (SERB), Department of Science and Technology (DST), and Government of India for financial support under an Early Career Research award (Grant ECR/2017/000822) and IIT Hyderabad for seed grant and research facilities. S. J. and G. P. would like to thank Ministry of Human Research Development and IIT Hyderabad for research fellowships. M.I. would like to thank DST India for research fellowship. Use was made of the Integrated Molecular Structure Education and Research Center X-ray Facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental Resource (NSF Grant ECCS-1542205), the State of Illinois, and the International Institute for Nanotechnology.

Uncontrolled Keywords:

Atoms; Barium compounds; Barium metallography; Crystal atomic structure; Energy gap; Inorganic compounds; Optical properties; Optical signal processing; Semiconducting silver compounds; Silver compounds; Silver metallography; Single crystals; Spectroscopic analysis

Subjects:

Chemistry

Divisions:

Department of Chemistry

Depositing User:

. LibTrainee 2021

Date Deposited:

23 Nov 2022 11:02

Last Modified:

23 Nov 2022 11:02

URI:

http://raiithold.iith.ac.in/id/eprint/11378