Elastic and thermal properties of the layered thermoelectrics BiOCuSe and LaOCuSe

Saha, SK and Dutta, G (2016) Elastic and thermal properties of the layered thermoelectrics BiOCuSe and LaOCuSe. In: PHYSICAL REVIEW B, 94 (12).

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Abstract

We determine the elastic properties of the layered thermoelectrics BiOCuSe and LaOCuSe using first-principles density functional theory calculations. To predict their stability, we calculate six distinct elastic constants, where all of them are positive, and suggest mechanically stable tetragonal crystals. As elastic properties relate to the nature and the strength of the chemical bond, the latter is analyzed by means of real-space descriptors, such as the electron localization function (ELF) and Bader charge. From elastic constants, a set of related properties, namely, bulk modulus, shear modulus, Young's modulus, sound velocity, Debye temperature, Gruneisen parameter, and thermal conductivity, are evaluated. Both materials are found to be ductile in nature and not brittle. We find BiOCuSe to have a smaller sound velocity and, hence, within the accuracy of the used Slack's model, a smaller thermal conductivity than LaOCuSe. Our calculations also reveal that the elastic properties and the related lattice thermal transport of both materials exhibit a much larger anisotropy than their electronic band properties that are known to be moderately anisotropic because of a moderate effective-electron-mass anisotropy. Finally, we determine the lattice dynamical properties, such as phonon dispersion, atomic displacement, and mode Gruneisen parameters, in order to correlate the elastic response, chemical bonding, and lattice dynamics.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Additional Information:	Copy right for this article belongs to the AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	03 Dec 2016 06:24
Last Modified:	03 Dec 2016 06:24
URI:	http://eprints.iisc.ac.in/id/eprint/55277

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