Isotope Effects on High-Pressure Water

Recent observations on superionic water reveal a rich phase behavior including dissociation, hydrogen melting, rapid hydrogen ion diffusion through an oxygen lattice, oxygen melting, and a transition from ionic to mostly electronic conduction. To better understand this complex phase diagram we explored its dependence on exchanging deuterium for hydrogen. D₂O was precompressed in diamond-anvil cells and then compressed through laser-driven shocks on the OMEGA laser at the University of Rochester’s Laboratory for Laser Energetics. Shock velocity and temperature were measured using the velocity interferometer system for any reflector and streaked optical pyrometer diagnostics and used to determine mechanical, thermal, and transport properties of heavy water to 500 GPa. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856.