Bond Lengths in the α-Ga2O3 Structure and the High-Pressure Phase of Ga2−xFexO3

Abstract

The crystal structure of α‐Ga₂O₃, which is isostructural with α‐corundum, has been refined from single‐crystal x‐ray diffraction data. The bond lengths have been determined to an accuracy of about 0.01 Å. The bond lengths in the GaO₆ octahedron are 2.077 and 1.921 Å. The short Ga–O distance corresponds to the oxygens forming the unshared face of the octahedron, whereas the long one corresponds to the shared face. Under high pressure and high temperature Ga_2−xFe_xO₃ undergoes a phase transition. The room‐temperature, room‐pressure phase is orthorhombic. In this structure the gallium ions have coordination numbers 4 and 6 while the iron ions have coordination number 6 only. The high‐temperature, high‐pressure phase is isostructural with α‐corundum so that all cations have coordination number 6.