Anomalous dynamical charges, phonons, and the origin of negative thermal expansion in Y2W3O12

Sumithra, S and Waghmare, UV and Umarji, AM (2007) Anomalous dynamical charges, phonons, and the origin of negative thermal expansion in Y2W3O12. In: Physical Review B: Condensed Matter and Materials Physics, 76 (2).

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Abstract

We use a combination of classical model and first-principles density functional theory calculations to study lattice dynamics of Y2W3O12 and identify phonons responsible for its negative thermal expansion (NTE). Born dynamical charges of various atoms are found to deviate anomalously from their nominal values. We find that the phonons with energy from 4 to 10 meV are the primary contributors to its NTE. These phonons involve rotations of the YO6 octahedra and WO4 tetrahedra in mutually opposite sense and collective translational atomic displacements, reflecting a strong mixing between acoustic and optic modes.

Item Type:	Journal Article
Publication:	Physical Review B: Condensed Matter and Materials Physics
Publisher:	The American Physical Society
Additional Information:	Copyright of this article belongs to The American Physical Society.
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	05 Mar 2010 08:02
Last Modified:	19 Sep 2010 05:56
URI:	http://eprints.iisc.ac.in/id/eprint/25954

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