Ab initio study of Cu diffusion in α-cristobalite

M. Zelený*, J. Hegedüs, A. S. Foster, D. A. Drabold, S. R. Elliott, R. M. Nieminen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)
62 Downloads (Pure)

Abstract

We have studied the geometries, formation energies, migration barriers and diffusion of a copper interstitial with different charge states with and without an external electric field in the α-cristobalite crystalline form of SiO2 using ab initio computer simulation. The most stable state almost throughout the band gap is charge q = + 1. The height of the migration barrier depends slightly on the charge state and varies between 0.11 and 0.18 eV. However, the charge has a strong influence on the shape of the barrier, as metastable states exist in the middle of the diffusion path for Cu with q = + 1. The heights and shapes of barriers also depend on the density of SiO 2, because volume expansion has a similar effect to increase the positive charge on Cu. Furthermore, diffusion coefficients have been deduced from our calculations according to transition-state theory and these calculations confirm the experimental result that oxidation of Cu is a necessary condition for diffusion. Our molecular dynamics simulations show a similar ion diffusion, and dependence on charge state. These simulations also confirm the fact that diffusion of ions can be directly simulated using ab initio molecular dynamics.

Original languageEnglish
Article number113029
Pages (from-to)1-21
Number of pages21
JournalNew Journal of Physics
Volume14
Issue numberNovember
DOIs
Publication statusPublished - Nov 2012
MoE publication typeA1 Journal article-refereed

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