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.

中文翻译：

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SrI2的应力驱动相变：原理研究

使用第一性原理计算研究了碘化锶（SrI ₂）在高达20 GPa的静水压力和非静水压力下的结构和电子性能。静水压缩时，SrI ₂经历了从13.2 GPa的Pbca结构到准分层Pbcm结构的相变，并且带隙随着压力的增加而变窄。在单轴压缩时，系统表现出很强的各向异性。沿着[010]，通过中间的亚稳Pbcm结构在大约16.8 GPa处观察到Pbca→Cmcm的相变，而沿着[100]和[001]，Pbca结构保持了细胞形状的变化。这些相变通过剪切模量，能带结构和状态密度进行了系统分析。在其单轴压缩过程中出现的合适带隙被用于光学和半导体应用。