First-principles theory of ionic diffusion with nondilute carriers

A. Van der Ven, G. Ceder, M. Asta, and P. D. Tepesch
Phys. Rev. B 64, 184307 – Published 25 October 2001
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Abstract

Many multicomponent materials exhibit significant configurational disorder. Diffusing ions in such materials migrate along a network of sites that have different energies and that are separated by configuration dependent activation barriers. We describe a formalism that enables a first-principles calculation of the diffusion coefficient in solids exhibiting configurational disorder. The formalism involves the implementation of a local cluster expansion to describe the configuration dependence of activation barriers. The local cluster expansion serves as a link between accurate first-principles calculations of the activation barriers and kinetic Monte Carlo simulations. By introducing a kinetically resolved activation barrier, we show that a cluster expansion for the thermodynamics of ionic disorder can be combined with a local cluster expansion to obtain the activation barrier for migration in any configuration. This ensures that in kinetic Monte Carlo simulations, detailed balance is maintained at all times and kinetic quantities can be calculated in a properly equilibrated thermodynamic state. As an example, we apply this formalism for an investigation of lithium diffusion in LixCoO2. A study of the activation barriers in LixCoOx within the local density approximation shows that the migration mechanism and activation barriers depend strongly on the local lithium-vacancy arrangement around the migrating lithium ion. By parametrizing the activation barriers with a local cluster expansion and applying it in kinetic Monte Carlo simulations, we predict that lithium diffusion in layered LixCoO2 is mediated by divacancies at all lithium concentrations. Furthermore, due to a strong concentration dependence of the activation barrier, the predicted diffusion coefficient varies by several orders of magnitude with lithium concentration x.

  • Received 6 April 2001

DOI:https://doi.org/10.1103/PhysRevB.64.184307

©2001 American Physical Society

Authors & Affiliations

A. Van der Ven and G. Ceder

  • Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139

M. Asta

  • Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208

P. D. Tepesch

  • Corning, Inc., Corning, New York 14831

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Issue

Vol. 64, Iss. 18 — 1 November 2001

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