The mantle is estimated to be planet Earths most massive volatile (e.g. H, C, S, N) storage reservoir, with interactions between crustal and mantle reservoirs dominate the surface inventory of volatile elements over geological time. Hydrous phase A is a link in the chain of overlapping high pressure minerals that ultimately transport water (or hydrogen) to the core mantle boundary in subjecting slabs. Despite its relevance there have been few studies of its thermoelastic parameters at elevated PT conditions. We propose to perform a simultaneous high pressure and high temperature neutron diffraction experiment on PEARL to refine the crystal structure and equation of state of hydrous phase A as part of our ongoing program to extend the range of PT conditions routinely available in the Paris-Edinburgh cell at ISIS.
