High pressure crystallography

A material’s properties and its chemical structure are strongly correlated. It is however very complex to predict properties from theoretical structures because of the number of important parameters. One of the parameters that are really important for the materials properties is the interatomic interactions. That means, how the atoms interact with each other and which type of energy (repulsive or attractive energies) that dominates the different bondings. When a pressure is applied to a crystal, the atoms are forced together which somehow causes the crystal to break – or to undergo a phase transition that reduce the total energy in the system.

Thereby, we can learn to understand how atoms in complicated systems interact and how these interactions influence the properties in the material. For example why a material can become superconducting or why the stability of a clathrate (as seen in the figure) depends on the guest molecules that can be placed in the clathrates cavities.