Pressure-induced structural transition of CsI and CsBr

Abstract
A pressure-induced phase transition of CsBr was found by using energy dispersive x-ray diffraction with a synchrotron x-ray source. The cubic phase CsBr was found to undergo transformation to a tetragonal crystal structure under high pressure similar to that recently reported for CsI. We suggest again that macroscopic elastic instability theory provides a possible explanation of this kind of phase transition.