Y3Fe0.5SiSe7: A new cation-deficient quaternary mixed transition metal chalcogenide with extremely low thermal conductivity

Niranjan, Manish K and Prakash, J. (2023) Y3Fe0.5SiSe7: A new cation-deficient quaternary mixed transition metal chalcogenide with extremely low thermal conductivity. Solid State Sciences, 138. p. 107133. ISSN 1293-2558

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Abstract

Single crystals of a new selenide, Y3Fe0.5SiSe7, have been synthesized by a reaction of elements at high temperatures inside a vacuum-sealed fused silica tube. The title phase crystallizes in the hexagonal noncentrosymmetric P63 space group (Pearson symbol hP23) at room temperature (RT), as established by a single-crystal X-ray diffraction study. The structure is non-stoichiometric with refined lattice parameters of a = b = 10.1971(1) Å, c = 5.9799(2) Å, and V = 538.49(2) Å3 (Z = 2). The asymmetric unit of the structure consists of six crystallographically independent atomic positions: one Y, one half-occupied Fe, one Si, and three Se sites. The building blocks of the structure are a distorted FeSe6 octahedron, YSe6 trigonal prism, and SiSe4 tetrahedron that are fused together via sharing of anions to create a three-dimensional periodic network. The charge-balanced formula of the structure can be achieved as (Y3+)3(Fe2+)0.5(Si4+)1(Se2−)7. A polycrystalline sample of Y3Fe0.5SiSe7 was also synthesized by the high-temperature reactions of stoichiometric amounts of elements. A direct bandgap value of 1.1(1) eV for the polycrystalline sample was estimated by a solid-state UV–Vis–NIR absorption spectroscopic study. A resistivity study on the polycrystalline Y3Fe0.5SiSe7 sample corroborates its semiconducting nature. The polycrystalline sample also shows an extremely low thermal conductivity value of ∼0.26 Wm−1K−1 at 773 K. The ab-initio optical and thermoelectric parameters of the title structure have been estimated from the electronic band structure. The relative bond strengths of Y, Si, and Fe atoms with Se atoms are investigated by the COHP study.

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IITH Creators:

IITH Creators	ORCiD
Niranjan, Manish K	http://www.orcid.org/0000-0002-4417-5107
Prakash, J.	http://www.orcid.org/0000-0002-4078-9662

Item Type:

Article

Uncontrolled Keywords:

Electronic structure calculations; Optical bandgap; Single-crystal X-ray diffraction; Solid-state synthesis; Thermal conductivity; Absorption spectroscopy; Atoms; Crystal atomic structure; Electronic structure; Energy gap; Fused silica; Iron; Iron compounds; Selenium; Selenium compounds; Spectroscopic analysis; Thermal conductivity; X ray diffraction; Electronic structure calculations; Low thermal conductivity; Optical-bandgap; Polycrystalline samples; Single-crystal X-ray diffraction; Solid-state synthesis; Synthesised; Transition metal chalcogenides; Transition-metal chalcogenides; X- ray diffractions; Single crystals

Subjects:

Physics
Physics > Modern physics
Chemistry
Chemistry > Analytical chemistry

Divisions:

Department of Chemistry
Department of Physics

Depositing User:

Mr Nigam Prasad Bisoyi

Date Deposited:

24 Sep 2023 10:46

Last Modified:

26 Sep 2023 05:18

URI:

http://raiithold.iith.ac.in/id/eprint/11692