Method and device for controlling crystallization

A method for controlling crystallization or recrystallization comprising:

• performing a vapour diffusion of at least one crystallization solvent in an isothermal system, said system comprising a sample of solid material and a vapour source diffusing the vapour, the solid material being initially at least partially amorphous and/or at least partially crystalline,
• crystallizing or recrystallizing the sample under the effect of the diffused vapour,
• at least during the crystallizing or recrystallizing, measuring heat received or given up by the system, the vapour source comprising said solvent for crystallizing said solid material, a method in which during the crystallization or recrystallization the quantities of heat exchanged within the system other than the heat of crystallization or recrystallization of the sample are less than approximately 10% of the heat of crystallization or recrystallization of the sample, and
• limiting a vapour diffusion rate in the system such that the vapour diffusion rate is less than 100 nano moles per second.