AI Article Synopsis
- Cesium triiodide (CsI3) undergoes a significant structural change from orthorhombic to trigonal when subjected to pressures above 1.24 GPa, as observed through synchrotron single-crystal X-ray diffraction.
- The transition involves a major reorganization of its polyiodide network, shifting from a layered structure to a three-dimensional one.
- Quantum chemical and phonon calculations indicate that while both phases are energetically similar at normal conditions, the trigonal structure is favored at high pressures and is dynamically unstable at ambient conditions.
Article Abstract
Structural evolution of cesium triiodide at high pressures has been revealed by synchrotron single-crystal X-ray diffraction. Cesium triiodide undergoes a first-order phase transition above 1.24(3) GPa from an orthorhombic to a trigonal system. This transition is coupled with severe reorganization of the polyiodide network from a layered to three-dimensional architecture. Quantum chemical calculations show that even though the two polymorphic phases are nearly isoenergetic under ambient conditions, the PV term is decisive in stabilizing the trigonal polymorph above the transition point. Phonon calculations using a non-local correlation functional that accounts for dispersion interactions confirm that this polymorph is dynamically unstable under ambient conditions. The high-pressure behavior of crystalline CsI can be correlated with other alkali metal trihalides, which undergo a similar sequence of structural changes upon load.
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| http://dx.doi.org/10.1021/acs.inorgchem.2c01690 | DOI Listing |
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