Phase transitions in GaSb to 110 GPa (1.1 Mbar)

The III-V compound GaSb was studied by energy-dispersive x-ray diffraction up to a pressure of 110 GPa with the use of a synchrotron source. The first transformation from the zinc-blende to the β-Sn structure confirmed earlier work. This was followed upon an increase in pressure by a new transformation to a simple hexagonal (SH) structure at 27.8±{}0.6 GPa. This is the first example of an SH structure in a III-V compound. A transition from the β-Sn to SH structure was predicted recently based on ab initio pseudopotential total-energy calculations. Upon a further increase in pressure the simple hexagonal structure transformed to another structure at 61.0±{}0.7 GPa which persisted to 110 GPa, the highest pressure to which III-V compounds have been studied.