Structure of GaSb to 35 GPa

The structural pressure dependence of GaSb has been determined to 35 GPa. The well-known phase transition at 7 GPa is found to be to a disordered orthorhombic structure with space group Imma, rather than to the {β}-tin structure previously reported. We find the Imma phase to be stable to at least 35 GPa, and do not observe the transition to a simple-hexagonal structure previously reported at 28 GPa. Striking similarities with the Imma phase of silicon are found in the pressure dependence of the lattice parameters and the variable atomic coordinate.