Novel group 14 nitrides

In recent years, a lot of work has been focused on the synthesis of novel carbon nitrides, especially crystalline C3N4 phases. Numerous attempts to synthesise the theoretically predicted solids have been published. This review summarises the theoretical work as well as the attempts to prepare carbon(IV) nitrides by chemical and physical vapour deposition, and in particular on the concepts and results of bulk synthesis routes. Although very interesting materials have been obtained, a comprehensive characterisation of a crystalline C3N4 phase is still missing. In 1999, a novel class of nitrides, which posses the spinel structure, has been discovered. The synthesis and properties of the high pressure phases γ-M3N4 with M = Si, Ge and the first tin nitride γ-Sn3N4 are reviewed. Related oxide nitride spinel compounds, other ternary phases such as Si/C/N as well as subnitrides, sialons and amorphous phases are mentioned briefly.