Pressure induced weakness of electrostatic interaction and solid decomposition in Cs−I compounds

This work utilized first-principles calculations and the CALYPSO structure search technique to systematically investigate the crystal structure stability of Cs x I y compounds under high pressures ranging from 0 to 500 GPa. Several new phases with both conventional and unconventional stoichiometries...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2023-09, Vol.25 (35), p.23448-23453
Main Authors: Geng, Yanlei, Li, Jianfu, Zhang, Zhaobin, Lv, Yang, Xu, Zhenzhen, Liu, Yong, Yuan, Jianan, Wang, Qinglin, Wang, Xiaoli
Format: Article
Language:English
Subjects:
Cesium
Charge transfer
Crystal structure
Decomposition
Enthalpy
First principles
Halides
High pressure
Internal energy
Metal halides
Stoichiometry
Structural stability
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Summary:This work utilized first-principles calculations and the CALYPSO structure search technique to systematically investigate the crystal structure stability of Cs x I y compounds under high pressures ranging from 0 to 500 GPa. Several new phases with both conventional and unconventional stoichiometries were predicted. Interestingly, we discovered a counter-intuitive phenomenon where Cs−I compounds decompose into Cs and I elemental solids under pressure. To understand the physical mechanism behind this pressure-induced decomposition, we examine the phenomenon from two distinct perspectives: enthalpy of formation and interatomic interactions. Our results suggest that the main cause is the weakening of electrostatic interactions leading to the decomposition, while the weak covalent interaction plays a minor role. From an energy perspective, the decrease in the formation of enthalpy (Δ H ) is primarily due to a reduction in the difference of internal energy (Δ U ). These findings provide valuable insights into the decomposition mechanism and high-pressure properties of alkali metal halides. The counterintuitive phenomenon of high-pressure charge transfer and decomposition may inspire new ideas and perspectives in the fields of geology and the study of alkali metal halides under extreme conditions. We have scrutinized the high-pressure decomposition of Cs−I compounds, considering both enthalpy of formation and interatomic interactions. Our findings offer valuable insights into alkali metal halide behavior amidst extreme conditions.
ISSN:1463-9076
1463-9084
DOI:10.1039/d3cp02343e