This technique has been used to develop dislocation free, purer and bigger single crystals. Among the hydrothermally-grown crystals, quartz is the most popular and technologically important one. Each year, over one million pounds of synthetic quartz are produced in the world to be used as piezoelectric crystal in filters, timing and frequency control applications.
Hydrothermal process has a geologic origin.
Minerals formed during the postmagmatic and metasomatic stages in the presence of water at elevated temperatures and presssures are considered to be of hydrothermal origin. This way, the geological conditions of crystal growth are replicated in the laboratory. A crystal grows under less thermal strain and thus may contain a lower dislocation density than when the crystal is grown from a melt where large thermal gradients are present. It can be used for all inorganic species, starting from native elements to the most complex silicates, germanates, phosphates and other compounds. It can be employed for large scale synthesis of piezoelectric, magnetic, optic, ceramic and many other special materials.