Pressure-induced disproportionation of cesium iodide

Abstract

X-ray diffraction and electrical conductivity measurements demonstrate that CsI undergoes pressure-induced, high-temperature decomposition to its constituent elements at pressures exceeding 45 GPa. Our results provide a natural explanation for the apparent discrepancy between previous shock-wave and static compression measurements performed on CsI. Also, our observations imply that the metallic phase of CsI is metastable and that changes in the electronic properties of the heavy alkali metals at high pressures strongly decrease the tendency of these elements to form ionic compounds.