Characterisation of the P-T phase diagram and thermal EoS of Ir via RH-DAC and X-ray diffraction

Iridium is one of the most incompressible element within the family of 5d metals and it is the only refractory metal with a face-centred cubic structure. It has a number of exceptional properties, such as: high shear modulus, chemical inertness, high thermal and phase stability. For these reasons it is a very good candidate as gasket material or as pressure standard for high temperature and high pressure diamond-anvil cell experiments. However, the stability of its fcc structure under pressure has been debated for years and so far there is not experimental evidences of its melting curve. Therefore, we propose to perform a thorough investigation of the P-T phase diagram of iridium up to 180 GPa and 1300 K combining resistively-heated DAC (RH-DAC) and x-ray diffraction techniques. In this way we will be able to point out any possible solid-solid phase transition or anomalies linked to a predicted core-level crossing electronic transition and,extract its PVT equation of state.