Phonons and oxygen diffusion in Bi2O3 and (Bi0.7Y0.3)2O3
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
We report investigation of phonons and oxygen diffusion in Bi2O3 and (Bi0.7Y0.3)2O3. The phonon spectra have been measured in Bi2O3 at high temperatures up to 1083 K using inelastic neutron scattering. Ab-initio calculations have been used to compute the individual contributions of the constituent atoms in Bi2O3 and (Bi0.7Y0.3)2O3 to the total phonon density of states. Our computed results indicate that as temperature is increased, there is a complete loss of sharp peak structure in the vibrational density of states. Ab-initio molecular dynamics simulations show that even at 1000 K in δ-phase Bi2O3, Bi-Bi correlations remain ordered in the crystalline lattice while the correlations between O-O show liquid like disordered behavior. In the case of (Bi0.7Y0.3)2O3, the O-O correlations broadened at around 500 K indicating that oxygen conductivity is possible at such low temperatures in (Bi0.7Y0.3)2O3 although the conductivity is much less than that observed in the undoped high temperature δ-phase of Bi2O3. This result is consistent with the calculated diffusion coefficients of oxygen and observation by QENS experiments. Our ab-initio molecular dynamics calculations predict that macroscopic diffusion is attainable in (Bi0.7Y0.3)2O3 at much lower temperatures, which is more suited for technological applications. Our studies elucidate the easy directions of diffusion in δ-Bi2O3 and (Bi0.7Y0.3)2O3.
Date Issued
2020-05-20
Date Acceptance
2020-04-14
Citation
Journal of Physics: Condensed Matter, 2020, 32 (33)
ISSN
0953-8984
Publisher
IOP Publishing
Journal / Book Title
Journal of Physics: Condensed Matter
Volume
32
Issue
33
Copyright Statement
© 2020 IOP Publishing Ltd. This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics: Condensed Matter. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at https://doi.org/10.1088/1361-648X/ab88f8. As the Version of Record of this article is going to be/has been published on a subscription basis, this Accepted Manuscript will be available for reuse under a CC BY-NC-ND 3.0 licence (https://creativecommons.org/licenses/by-nc-nd/3.0/) after a 12 month embargo period.
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/32289754
Subjects
Ab-initio
Diffusion
Molecular dynamics
Order disorder
Phase Transition
Phonon
Publication Status
Published
Coverage Spatial
England
Date Publish Online
2020-04-14