Crystalline state in a pressure region of proceeding amorphization of SnI4

Room-temperature compression with a diamond-anvil cell without pressure-transmitting media has detected SnI${}_4$4's pressure-induced solid-state amorphization at around 15 GPa. Multianvil apparatus compression employed in this study shows us an entirely different aspect; instead of undergoing amorphization, SnI${}_4$4 remains crystalline, which is stabilized by heating from room temperature. This crystalline state could be the metallic phase, the high pressure modification, whose existence has been known, but the structure remains unresolved. Surprisingly, this crystalline state transforms to another crystalline state, not yet reported thus far, before returning to the ambient phase upon isothermal decompression at about 530 K and 640 K. Combined Angle- and Energy-Structural Analysis and Refinement (CAESAR), devised by Wang et al. (J Appl Cryst. 2004;37;947), with which to convert energy-dispersive diffraction patterns to those of angle-dispersive ones, is demonstrated as a profitable approach that can compensate a standard energy dispersive measurement.