title: Superionic Phases of the 1:1 Water-Ammonia Mixture.
abstract: We report four structures for the 1:1 water-ammonia mixture showing superionic behavior at high temperature with the space groups P4/nmm, Ima2, Pma2, and Pm, which have been identified from evolutionary random structure search calculations at 0 K. Analyzing the respective pair distribution functions and diffusive properties the superionic phase is found to be stable in a temperature range between 1000 and 6000 K for pressures up to 800 GPa. We propose a high-pressure phase diagram of the water-ammonia mixture for the first time and compare the self-diffusion coefficients in the mixture to the ones found in water and ammonia. Finally, possible implications on the interior structure of the giant planets Uranus and Neptune are discussed.
authors.affiliation: University of Rostock: Institute of Physics, University of Rostock , Albert-Einstein-Straße 23-24, 18059 Rostock, Germany.|Lawrence Livermore National Laboratory , 7000 East Avenue L-413, Livermore, California 94550, United States.
authors.forename: Mandy
authors.initials: M
authors.lastname: Bethkenhagen
authors.affiliation: University of Rostock: Institute of Physics, University of Rostock , Albert-Einstein-Straße 23-24, 18059 Rostock, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cebulla
authors.affiliation: University of Rostock: Institute of Physics, University of Rostock , Albert-Einstein-Straße 23-24, 18059 Rostock, Germany.
authors.forename: Ronald
authors.initials: R
authors.lastname: Redmer
authors.affiliation: Lawrence Livermore National Laboratory , 7000 East Avenue L-413, Livermore, California 94550, United States.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Hamel