A
supercritical fluid (SCF) is any substance at a
temperature and
pressure above its
critical point, where distinct liquid and gas phases do not exist. It can
effuse through solids like a gas, and
dissolve materials like a liquid. In addition, close to the critical point, small changes in pressure or temperature result in large changes in
density, allowing many properties of a supercritical fluid to be "fine-tuned". Supercritical fluids are suitable as a substitute for
organic solvents in a range of industrial and laboratory processes.
Carbon dioxide and water are the most commonly used supercritical fluids, being used for
decaffeination and
power generation, respectively.