Solvothermal processes and the synthesis of nitrides

Abstract

Nitrides constitute an important class of materials due to their physical properties. In this way, all processes related to their synthesis or shaping are of relevant interest. A solvothermal process can be described as a reaction between precursors in a close system in the presence of a solvent and at a temperature higher than the boiling point of the solvent, with pressure being consequently involved. Depending on the pressure and temperature, the solvent is in sub- or supercritical conditions. The system precursors/solvent can be either homogeneous or heterogeneous. Concerning nitrides, solvothermal processes have been mainly developed in three domains:

1.	the preparation of novel compositions
2.	the elaboration of nanocrystallites well defined in size and morphology
3.	the crystal-growth of functional nitrides such as GaN.

Considering the synthesis of novel nitrides, different solvothermal reactions can be used versus the nitriding agent (N³⁻ or N) and the nature of the solvent (nitriding solvent or non-reactive solvent). Different examples will be given and the potentialities of solvothermal processes in the preparation of novel nitrides will be discussed.

Keywords:

• solvothermal processes
• nitrides
• synthesis
• nanocrystallites
• crystal growth
• solvothermal c-BN preparation