High pressure study of AlP: Transformation to a metallic NiAs phase

Abstract

The crystal structure and optical reflectivity of AlP has been studied in a diamond anvil cell using energy dispersive x-ray diffraction to 43 GPa and micro-optical reflectance spectroscopy to 36 GPa. AlP undergoes a first order phase transformation from zincblende to a NiAs structure which exhibits metallic reflectivity in the near-infrared. The decrease in volume on transformation is 17%±1%. The transformation is reversible but has large hysteresis. The equilibrium transformation pressure is 9.5±5 GPa.