Hydrothermal/Solvothermal Crystal Growth: an Old but Adaptable Process

Abstract Hydrothermal crystal growth can be described as a low temperature process under pressure using an aqueous solution as the solvent. The temperature gradient controls the transport phenomenon from the nutrient to the seeds. The solvothermal term is generally used when the solvent is a non‐aqueous solution. Different aspects will be particularly discussed: (a) The principle of hydrothermal/solvothermal crystal growth processes. (b) A brief history of the development of such processes. (c) The main factors involved during the crystal growth and their impact on the quality of the resulting macroscopic single crystals. (d) How these physical and chemical factors can be optimized to improve the quality of the crystals. The conclusions focus on the future developments of hydrothermal or solvothermal crystal growth processes.