Stress‐Driven Phase Transitions of SrI2: A First‐Principles Investigation

Abstract

The structural and electronic properties of strontium iodide (SrI2) under hydrostatic and nonhydrostatic compressions up to 20 GPa are investigated using first‐principles calculations. Upon hydrostatic compression, SrI2 undergoes a phase transition from the Pbca structure to a quasilayered Pbcm structure around 13.2 GPa, and the bandgap narrows with increasing pressure. Upon uniaxial compression, the system exhibits strong anisotropy. Along [010], a Pbca → Cmcm phase transition is observed at about 16.8 GPa via an intermediate metastable Pbcm structure, whereas along [100] and [001], the Pbca structure remains with cell shape changed. These phase transitions are systematically analyzed with shear moduli, band structures, and densities of states. The suitable bandgaps manifested during its uniaxial compression are exploited for optical and semiconductor applications.