Diffraction studies of the high pressure phases of GaAs and GaP

Abstract

High pressure structural phase transitions of GaAs and GaP have been studied by energy dispersive x-ray diffraction with the radiation from the Cornell High Energy Synchrotron Source. GaAs began to transform at 172±7 kbar to an orthorhombic structure possibly belonging to space group Fmmm. GaP transformed to a tetragonal β-Sn type phase at 215±8 kbar. Although pressure transmitting media were used to minimize shear stresses in the specimens, the high pressure diffraction results were interpreted as showing evidence for planar defects in the specimens.