Dynamics of pattern formation in layered materials: computer simulations of intercalation and deintercalation

Abstract

Three-dimensional Monte Carlo simulations of intercalation and deintercalation of microcrystals are presented. The kinetic Ising model used represents intercalation compounds as assemblies of interacting elementary intercalate islands. Real-space pictures of the microscopic processes and (00l) structure factors are given. The intercalate transport and cooperative effects leading to stage ordering and domain formation are investigated. Surface effects and elastic energy barriers are considered. Well-ordered stage 2 structures grow from pristine host crystals in either a multidomain or essentially single domain mode. For any guest–host combination, either mode can be selected by a suitable choice of the physical nature of the guest reservoir. Growth of high stages results in stage-disordered Daumas–Hérold domains because the formation of stage-ordered structures is not favored thermodynamically. Deintercalation from stage 1, with the reservoir chemical potential below the intercalation threshold, proceeds through a stage 2 domain structure that grows as a deintercalation front moves through the crystal. The in-plane pattern of stage 2 islands, which forms, is remarkably stable during this process. Eventually a residue compound forms, with some runs of galleries completely empty while in others the intercalate is self-trapped.