High-pressure structural phase transition in indium

A pressure-induced structural phase transition of indium has been found at 45 GPa using angle-dispersive powder-x-ray-diffraction techniques. The crystal structure of the high-pressure phase In(II) has been determined to be face-centered orthorhombic, which is stable to at least 93 GPa. In(II) is heavily deformed under uniaxial stress. While the volume change at the transition is very close to zero, the transition is likely to be first-order, judging from the coexistence of the low- and high-pressure phases over a wide range of pressure. The structure of In(II) is related to the low-pressure tetragonal phase through a simple orthorhombic distortion, which is in good accord with the structural trends expected from a previous pseudopotential theory.