Ab initio study of Cu diffusion in α-cristobalite

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.

DOI

10.1088/1367-2630/14/11/113029

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Zelený , M , Hegedüs , J , Foster , A S , Drabold , D A , Elliott , S R & Nieminen , R M 2012 , ' Ab initio study of Cu diffusion in α-cristobalite ' , New Journal of Physics , vol. 14 , no. November , 113029 , pp. 1-21 . https://doi.org/10.1088/1367-2630/14/11/113029

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https://urn.fi/URN:NBN:fi:aalto-201805222597

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[article-cris] Perustieteiden korkeakoulu / SCI

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Ab initio study of Cu diffusion in α-cristobalite

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