Hydrothermal synthesis is a process in aqueous media at elevated temperature (T>25oC) and
pressure (P>100 kPa) to crystallize ceramic materials directly from solution. Syntheses are usually
conducted at autogeneous pressure, which corresponds to the saturated vapor pressure of the solution
at the specified temperature and composition of the hydrothermal solution. Mild conditions are
preferred for commercial processes where temperatures are less than 350 oC and pressures less than
approximately 50 MPa.
Hydrothermal synthesis offers many advantages over conventional and non-conventional
inorganic material synthetic methods. All forms of ceramics can be prepared with hydrothermal
synthesis, namely powders, fibers, and single crystals, monolithic ceramic bodies, and coatings on
metals, polymers, and ceramics. There are far fewer time- and energy-consuming processing steps since
high temperature calcination, mixing, and milling steps are either not necessary or minimized.