The phrase "hydrothermal method" refers to a variety of processes used to crystallise compounds from highly heated aqueous solutions at high vapour pressures. Hydrothermal is a word with geology roots. Hydrothermal phase equilibria have been researched by geochemists and mineralogists since the turn of the twentieth century. The majority of the work was done by George W. Morey at the Carnegie Institution and Percy W. Bridgman at Harvard University to create the groundwork essential for the confinement of reactive media in the temperature and pressure range where the majority of hydrothermal research is done. A technique for creating single crystals that relies on the solubility of minerals in hot water under intense pressure is known as hydrothermal synthesis.