Structural studies of gadolinium at high pressure and temperature

High pressure and high temperature angle-dispersive x-ray diffraction measurements on gadolinium were performed up to 93 GPa and nearly 2500 K using argon as pressure medium. Our room temperature measurements confirmed the transition pressures reported in a previous study carried out using nitrogen as pressure medium, solving former discrepancies found in the literature. A new phase was observed above 1200 K between 39 GPa and 52 GPa. Additionally, the structure of the previously observed dfcc and post-dfcc phases was determined, being the space group symmetry of the post-dfcc phase (C2/m), different from what was predicted before. Finally, the room temperature equation of state was determined for Gd and its pressure-temperature phase diagram redefined.