Practically all chemists knows the necessity of recrystallization as a method of purification of solid products . Less known, this method is useful for make growing crystals. The goal in growing crystals for X- Ray diffraction experiment is to grow sigle crystals. The optimum size for a crystal is about 0.2 to 0.4 mm in at least two directions of space. The factors during crystal growth which affect the size of the crystal are:
- The solubility of the compound in the solvent chosen for recrystallization
- Mechanical agitation to the system
Solvent: Choose a solvent in which your compound is moderately soluble. If the solute is too soluble, this will result in small crystal size. And supersaturated solutions tends to give crystals which are too small in size too.
Mechanics: Mechanical disturbance of the crystal growing results in smaller crystals. The crystals have to grow with a minimum of disturbance. So, don’t check how your crystals are growing every days!!! Set up the crystals growing attempt in a quiet, out of the way place for a week.