Pressure-induced decomposition of cadmium iodide

Abstract

A static pressure-induced decomposition of cadmium iodide into cadmium and iodine solids is reported in this work using a structure prediction approach combined with first-principles calculations. By compression, CdI2 decomposes into Cd and I at 61.5 GPa, which goes against the common intuition that applying pressure makes the material stable and dense. The increase in the term and with pressure between the compound and the element contributes to the increase in the enthalpy difference, leading to the decomposition of CdI2. On the other hand, the analyses of interatomic interaction demonstrate that under the action of pressure, the decrease of charge transfer between atoms leads to the decrease of the Coulomb interaction, which finally induces CdI2 to decompose into Cd and I solids. Our work represents a significant step toward an understanding of the high-pressure behaviors of Cd-I systems and draws attention to the influence of pressure parameters in certain materials.