Pressure-Induced Amorphization and Recrystallization of SnI2

The high-pressure behavior of SnI2 has been investigated in a combined experimental and theoretical study by angle-dispersive X-ray diffraction, Raman scattering measurements, and ab initio calculations. Both the Raman and XRD results confirm that the SnI2 crystal undergoes a gradual crystal to amorphous transition and subsequently recrystallizes to a new crystal structure upon compression. The intensity of the Sn–I symmetric stretching mode greatly decreases and manifests a red shift at 2.15 GPa in Raman spectra. The XRD patterns show a bonding break phenomenon before the pressure-induced amorphization. We propose that the bond breaking between neighboring layers leads to the formation of the amorphous phase under high pressure. The sample recrystallizes into a new high-pressure crystal phase at 33.18 GPa. The experimental and theoretical results provide a good candidate structure for the recrystallized phase with C2/m space group.