Pressure and temperature dependent structure of zircon type ThGeO 4

Abstract

Herein we report the results of high pressure diffraction studies of zircon type ThGeO4. ThGeO4 exhibits anisotropic compressibility with the average compressibility along a-axis (20.8 × 10-4/GPa) larger than that along c-axis (9.98 × 10-4/GPa). Fitting the pressure dependence unit cell volume to 3rd order Birch-Murnaghan equation of states, the zero pressure bulk modulus (Ko) and volume (V o) of 166(5) GPa and 341.6(3) Å3, respectively have been obtained. Preliminary studies on temperature dependent neutron and x-ray diffraction studies on ThGeO4 revealed anisotropic expansion behaviour with larger expansion coefficient along c-axis compared to a-axis. No structural transition under temperature or pressure is observed in between ambient pressure to 10 GPa and in the temperature range of 25 to 1273K.