High pressure structural phase transitions in CsCdCl3

Abstract High pressure studies reveal two phase transitions for CsCdCl 3 up to 125 kbar in the presence of traces of water. At ambient pressure, CsCdCl 3 (phase I) is transparent and it transforms to an opaque phase II at 2.6 kbar. On further pressure increase to about 22 kbar, CsCdCl 3 undergoes a second phase transition to another transparent phase (III). When water is absent, the opaque phase II cannot be observed; instead a transparent to transparent phase transition takes place below 12 kbar. These phase transitions are thought to be a series of transitions from a face-shared structure to a corner-shared structure. The transitions are reversible and very sluggish, in contrast to the irreversible phase transitions found in CsSnCl 3 .