Crystal+Growth

=Crystal Growth=

It has generally been much harder to understand the physical mechanism of crystal growth in comparison to nucleation. Since crystal growth is very dependent on the crystal surface, it can lead to extremely complicated growth mechanisms that are not necessarily of interest in this wiki. In the simplest terms, crystal growth is established when atoms or molecules **join** a crystal through the attachment at a **kink site** when they both reach the same chemical potential.

The Energy Landscape:
An easy way to build the thinking process of the crystal growth mechanism is through the **energy landscape**. All characteristics of a crystal, including the phase, habit, and growth rate, are determined by the shape of this landscape.



The mechanism is first thought of as being a **phase transition**. In this phase transition, the transformation of matter from a state of high free energy in a solvated state to a state of low energy in the crystal lattice takes place. Varying the heights of the barriers shown in the above figure (b) in this energy landscape helps control the growth kinetics, and select the final or intermediate steps.

The Importance of the Kink Site:
As mentioned above, crystal growth occurs when an atom attaches itself to a crystal through a **kink site**. It is important to note that the atom must attach at this **kink site** in the crystal growth mechanism as the bonds are much stronger when attached at this site (more likely to stick) than it is on any other site of the crystal surface. Molecues can either enter these kink sites directly from solution or after adsorbing and diffusing across the flatter regions (terraces).



The crystal growth mechanism becomes more complicated as the face of the crystal structure becomes more complex. Crystal growth is characterized into many different categories corresponding to the surface a crystal may posses. Each one of these crystal surfaces are analyzed differently, and can be further evaulated by different equations that govern each particular crystal surface. The video below illustrates the inhibition of one of the many different types of crystal growth: spiral crystal growth.

media type="file" key="crystal_growth.swf" width="360" height="360" align="center"

Back to Kinetic Inhibition