Regensburg 2010 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 11: Topical Session Glass Dynamics IV
MM 11.4: Talk
Monday, March 22, 2010, 17:15–17:30, H16
Proton dynamics in sodium silicate melts studied with high temperature high pressure QENS — •Fan Yang1, Andreas Meyer1, Tobias Unruh2, and Eugene Mamontov3 — 1Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln, Germany — 2Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), TU München, 85748 Garching, Germany — 3Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6475, USA
We apply quasielastic neutron scattering method under high temperature high pressure condition to investigate water dynamics in hydrous silicate melts. Neutron scattering offers the possibility to access pure proton dynamics via contrast variation by isotope substitution and to understand the water transport mechanisms in great detail. With the results from the time-of-flight spectrometer TOFTOF at FRM II in combination with the ones from the backscattering spectrometer BASIS at SNS, we are able to access a microscopic dynamic time window from 0.2 picosecond up to of about 800 picoseconds. Experiments on hydrous sodium silicate melts with 10 mol% (total) water concentration have been performed at 4 different temperatures under a constant pressure of 200 MPa. Our results show that the proton dynamics in hydrous silicate melts can be fitted into a glass-glass transition scenario under the frame work of the mode coupling theory.