Crystal growth

Crystal Growth is a major stage of crystallization that occurs after nucleation. It involves the addition of new atoms, ions and other materials to the crystal base to form the lattice of the crystal.

Nucleation

Nucleation is the first stage in the crystallization process. It is a localized physical process that involves the budding of lattice points. Nucleation is a slow process because in order for it to start, the atoms or ions have to be able to become attracted to one another. Nucleation in the case of crystals occurs when there is a supersaturated system and the sites start to cluster on the nanometer scale. These sites when stable become the nuclei or the start of the crystal. The sites have a higher concentration of the solution that is being used to make the crystal, and only once they are stable will they start to be nuclei. However, if the nuclei sites are unstable, they will redissolve back into the solution to try again later. The nuclei need to be at a critical size in order for nucleation to continue over to the crystal growth stage. There are two ways that a solution can go through nucleation: homogeneous nucleation and heterogeneous nucleation.

Homogeneous Nucleation

Homogeneous nucleation occurs when the solution is made up entirely of a uniform content. An example of this is purified water. This typically takes the longest as purified solutions have a lower energy state that they need to reach in order to nucleate. This energy state is lower than their normal ground state energy and it has to be drained off in order for the nucleation to happen.

Examples of Homogeneous Nucleation

• Purified Water freezes at -40 degrees Celsius
• Perfect Diamonds have no impurities