Constraining the platinum liquid-vapor phase boundary and critical point with fluid flyer experiments

We determine the temperature and density on the platinum (Pt) liquid-vapor coexistence (L-V) curve. Pt was shock melted then isentropically released to vacuum; the released material then acted as a secondary flyer and impacted a window with a well-established Hugoniot. These liquid flyer impacts produced reflecting shocks in the window which were measured using PDV and VISAR. Visible and near infrared pyrometry measured light radiated off the released metal. We calculate density using the velocimetry from each window and impedance matching techniques. Our density and temperature states are then compared to Density Functional Theory predictions. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. SAND2025-01422A