First-principles reinvestigation of bulk WO3

Hamdi, Hanen and Salje, Ekhard K. H. and Ghosez, Philippe and Bousquet, Eric (2016) First-principles reinvestigation of bulk WO3. Physical Review B, 94 (24). ISSN 1098-0121, ESSN: 1550-235X DOI 10.1103/PhysRevB.94.245124

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Official URL: http://doi.org/10.1103/PhysRevB.94.245124

Abstract

Using first-principles calculations, we analyze the structural properties of tungsten trioxide WO3. Our calculations rely on density functional theory and the use of the B1-WC hybrid functional, which provides very good agreement with experimental data. We show that the hypothetical high-symmetry cubic reference structure combines several ferroelectric and antiferrodistortive (antipolar cation motions, rotations, and tilts of oxygen octahedra) structural instabilities. Although the ferroelectric instability is the largest, the instability related to antipolar W motions combines with those associated to oxygen rotations and tilts to produce the biggest energy reduction, yielding a P21/c ground state. This nonpolar P21/c phase is only different from the experimentally reported Pc ground state by the absence of a very tiny additional ferroelectric distortion. The calculations performed on a stoichiometric compound so suggest that the low-temperature phase of WO3 is not intrinsically ferroelectric and that the experimentally observed ferroelectric character might arise from extrinsic defects such as oxygen vacancies. Independently, we also identify never observed R3m and R3c ferroelectric metastable phases with large polarizations and low energies close to the P21/c ground state, which makes WO3 a potential antiferroelectric material. The relative stability of various phases is discussed in terms of the anharmonic couplings between different structural distortions, highlighting a very complex interplay.

Item Type: Article
Uncontrolled Keywords: 2016AREP; IA72;
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
08 - Green Open Access
Journal or Publication Title: Physical Review B
Volume: 94
Identification Number: 10.1103/PhysRevB.94.245124
Depositing User: Sarah Humbert
Date Deposited: 24 Feb 2017 12:07
Last Modified: 02 Mar 2017 20:50
URI: http://eprints.esc.cam.ac.uk/id/eprint/3831

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