HP-HT characterization of the phase diagram of ruthenium

Ruthenium (Ru) is a 4d transition metal which is a member of the group 8 of the periodic table. It exhibits only a single electron in its highest occupied atomic orbital, making it unique amongst the group 8 elements. Surprisingly, little is known about the behaviour of Ru under HP-HT conditions despite the considerable attention which the transition metals attract in general. Here we propose to perform a detailed characterisation of the Ru phase diagram up to 100 GPa and 6000 K. The melting curve of Ru will be characterised experimentally for the first time, and the validity of the predicted hcp → fcc transition will be tested. If confirmed, the transition would constitute the first structural phase transition observed in Ru.