A batch hydrothermal reactor is great for crystallising inorganic materials, e.g. zeolites, complex oxides at relatively low temperatures and at high pressure; similar processes occur over hundreds of years, deep under the earths crust. The problems with batch hydrothermal reactions are really that they can be slow as the reactor has to heat up then cool down. In our CHFS, technique, we can make nanoparticle ceramics in a rapid and continuous manner in the space of minutes or seconds (uses supercritical water). The ability to rapidly precipitate crystalline inorganic materials can give access to kinetic phases or combinations of particle properties that are difficult to achieve using other more conventional methods.