Pressure-induced decomposition of cadmium iodide

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 61.5GPa, which goes against the common intuition that applying pressure makes the material stable and dense. The increase in the Delta PV term and Delta U 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. Copyright (C) 2022 EPLA

Automated summary

This work reports the static pressure-induced decomposition of cadmium iodide into cadmium and iodine solids using a structure prediction approach combined with first-principles calculations. The decomposition of CdI2 into Cd and I occurs at 61.5GPa, contrary to the common intuition that pressure stabilizes and densifies materials. The increase in the enthalpy difference between the compound and the element, resulting from the increase in the Delta PV term and Delta U with pressure, contributes to the decomposition of CdI2. On the other hand, the decrease in charge transfer between atoms under pressure leads to a decrease in the Coulomb interaction, ultimately inducing the decomposition of CdI2 into Cd and I solids. This work represents a significant advancement in understanding the high-pressure behaviors of Cd-I systems and highlights the influence of pressure parameters in certain materials.