Compound crystals

Graphite nanoparticles are known to be unstable due to the abundance of rim atoms with dangling bonds, closing into fullerenes and nanotubes under appropriate conditions. It was proposed in 1992 that this property is common also to nanoparticles of inorganic layered materials rather than being limited to carbon. Indeed, inorganic fullerene-like nanoparticles (IF) and inorganic nanotubes (INT) were produced initially from the layered materials WS₂ and MoS₂, and subsequently from numerous other layered compounds. The state of the art in this field is described briefly in this review. This chapter reviews the main methods used for IF and INT synthesis and discusses the relations between the different mechanisms and the resulting morphologies. Emphasis is placed on methods reported recently. The main differences between the morphologies are presented using WS2 and MoS₂ as representatives of the inorganic IF/INT family. The measured properties of W(Mo)S₂ IF and INT are further examined and compared with theoretical calculations.Finally, current applications of WS₂ and MoS₂ IF and INT are reviewed, highlighting recent advances in the fields of tribology and nanocomposite materials.