High-pressure synchrotron X-ray diffraction study of the pyrochlores: Ho₂Ti₂O₇, Y₂Ti₂O₇and 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.