Professor R S McWilliams

I study high pressure and high temperature states of matter in the laboratory to address questions of scientific and technological interest. I am interested in materials relevant to natural systems such as planetary interiors and to technologies such as energetic materials and inertial confinement fusion. I develop and use ultrafast methods to create, sustain, and study extreme states. These techniques use the diamond-anvil cell (static compression) and laser-driven shock compression (dynamic compression) to generate particular extreme states. I visit facilities worldwide for access to high power laser systems, synchrotron radiation, and other special instrumentation. I characterize fundamental material properties including strength, elastic moduli, optical properties, and melting points and examine how extreme conditions can be used to synthesize new materials.

[2026] High-Pressure Investigation of the I−N System: Discovery of the Nitric Ozonide [N3]3− (“Ozonitride”) Species and Multicenter Bonding in Iodine Frameworks [2026] Melting Temperature of Bismuth to 55GPa using SynchrotronX-ray Phase Contrast Imaging [2026] High-pressure formation and characterization of a boron carbide polymorph featuring bent C–B–C chains [2026] Metrology for femtosecond pulsed x-ray heating in diamond anvil cell experiments at the European XFEL: Revisiting the iron phase diagram up to 150GPa [2025] X-ray thermal diffuse scattering as a texture-robust temperature diagnostic for dynamically compressed solids