A method for intercalation of lithium in layered dichalcogenide crystals.

Lithium intercalation compounds of transition metal dichalcogenides have generated considerable interest because of fascinating physical properties such as charge density waves, two-dimensional ordering, and superconductivity, and because of their possible utility in secondary lithium batteries. Many of the physical property measurements of interest have not been done because until now the intercalation compounds have been available only as polycrystalline powders. This paper reports a new intercalation technique that allows preparation of large area single crystals. The technique involves equilibration of Li through the vapor phase between a polycrystalline source of the desired composition and a crystal. Crystals of TiS(2), 2H-TaS(2), and 2H-TaSe (2) have been intercalated to date. The method maintains crystallinity and allows good control over the stoichiometry.