Introduction of supercooled liquid
Under a certain pressure, when the temperature of the liquid is lower than the freezing point of the liquid under the pressure, and the liquid still does not solidify, the phenomenon is called supercooling. The liquid at this time is called supercooling liquid. According to the Kelvin formula, the smaller the crystal particles, the higher the vapor pressure, and the crystal particles cannot be produced at the normal freezing point. Only when the liquid is supercooled to a certain temperature, and the equilibrium vapor pressure of the crystal particles is equal to the equilibrium vapor pressure of the liquid, can a new phase be formed. The key to avoiding supercooling is to promote the smooth generation of new phase crystal nuclei. To this end, a small amount of crystals can be added as new phase seeds when the liquid is cooled to near the freezing point. When the liquid reaches the freezing point, it will automatically precipitate on the surface of these crystal particles; at the same time, it is necessary to strengthen stirring.