Phase transition kinetics in lattice models of intercalation compounds

Abstract

A lattice fluid model is considered to demonstrate phase transition kinetics and nanostructuring of intercalation compounds. Particles perform thermally activated hops between lattice sites. Attractive nearest neighbor interparticle interactions are taken into account. In this case, when the lattice fluid system temperature is below critical it decomposes into two phases: rarefied phase of low concentration (lattice gas) and condensed phase of high concentration (lattice liquid). The approach based on the nonequilibrium distribution function that depends on time through local values of the chemical potential is used to formulate the kinetic equation for lattice fluid concentration evolution. The nonequilibrium versions of the mean field, quasichemical and diagram approximations are used for representing the two-site distribution functions in terms of the concentration distribution. During evolution, uphill diffusion leads to depleting the layers nearest to the stepwise perturbation. This process creates conditions for uphill diffusion on more distant layers. The process lasts until the nanostructuring closes due to periodic boundary conditions. The system decomposes into nanosized strips of low (lattice gas) and high (lattice liquid) concentration. The final concentration distribution depends on the width and height of the initial perturbation. The process of particle escape from the system is investigated as well.