What are crystal phase diagrams?
A crystal phase diagram is a phase diagram that shows the conditions under which the different crystal phases of a substance can exist at equilibrium.
An ordinary phase diagram shows the temperatures and pressures at which solid, liquid, and gas phases can occur at equilibrium.
You are probably familiar with the phase diagram of water.
Polymorphic substances have multiple crystal phases.
For example, solids such as ice can exist in 17 crystal forms.
We can extend the normal phase diagram of water to show these forms, and then we have a crystal phase diagram.
There are numerous triple points in the diagram, and some of the boundaries have yet to be established.