High-pressure synchrotron X-ray diffraction study of the pyrochlores: Ho₂Ti₂O₇, Y₂Ti₂O₇ and Tb₂Ti₂O₇

Abstract

Synchrotron-based X-ray diffraction was used to study the phase diagrams and determine the compressibilities of the pyrochlore rare-earth titanates Ho₂Ti₂O₇, Y₂Ti₂O₇ and Tb₂Ti₂O₇ to ~50 GPa. The bulk moduli of the cubic phase of these materials were calculated to be 213±2, 204±3 and 199±1 GPa, respectively. The onset of a structural phase change from cubic to monoclinic was observed near 37, 42 and 39 GPa, respectively. The bulk modulus for the high pressure monoclinic phase of Y₂Ti₂O₇ has been determined to be 185±3 GPa.