Cation intercalation under a host restructuring. Application to crystalline LixWO3 and NaxWO3 compounds

Employing an elastic lattice gas (LG) model we investigate the intercalatio n of ions into a host material, undergoing a sequence of structural transfo rmations (monoclinic --> tetragonal --> cubic). It is shown that an effecti ve potential for the ions results from the intercalation-induced restructur ing of the host. This interaction induces distinct peaks (one is sharp, whi le the other is broad) in the current-concentration diagram. The sharp peak signals a droplet formation around the domain walls separating the host do mains of different symmetry (monoclinic --> tetragonal). The broad peak may be associated with a continuous (order-disorder) transition (tetragonal -- > cubic). Theoretical results agree well with experimental data for LixWO3 and NaxWO3. (C) 2001 Published by Elsevier Science Ltd.