Hydrothermal synthesis: a natural process exploited for the synthesis of compounds with controlled size and morphology

Hydrothermal processes are of great relevance in nature, being among the ways in which rocks and minerals are formed or transformed: the term hydrothermal is in fact of geological origin. The study of mineral genesis and transformation has been the driving force for the earlier studies of crystallisation mechanisms, followed by the interest in the formation of synthetic gems, like emerald and ruby. However, today the number of synthetic compounds exceeds the variety of phases reproduced from nature. The hydrothermal process is, in fact, unique for the synthesis of new phases, as well as for the control of size and morphology of the produced crystals. We will show examples of systems that can be synthesised in the laboratory with good control over particle morphology, as well as new emerging processes to obtain dense ceramics at low temperature.