Nucelation or Crystallization Temperature

The nucleation or crystallization temperature T_n is the temperature at which the cristal growth starts (nucleation) and is determined from the first deviation of the DSC signal from the baseline. The nucleation is a stochastic process that depends on the purity of the PCM, the sample volume, the interface to the measuring vessel and the cooling rate. Therefore, the nucleation temperature is subject to a certain degree of distribution, which is usually greater than the measurement uncertainties of a DSC instrument. Besides the nucleation or crystallization temperature as material property, on system level an isothermal equilibrium temperature depending on certain boundary conditions is also often named as crystallization temperature.