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Title: Solid-state diffusion in amorphous zirconolite

We discuss how structural disorder and amorphization affect solid-state diffusion, and consider zirconolite as a currently important case study. By performing extensive molecular dynamics simulations, we disentangle the effects of amorphization and density, and show that a profound increase of solid-state diffusion takes place as a result of amorphization. Importantly, this can take place at the same density as in the crystal, representing an interesting general insight regarding solid-state diffusion. We find that decreasing the density in the amorphous system increases pre-factors of diffusion constants, but does not change the activation energy in the density range considered. We also find that atomic species in zirconolite are affected differently by amorphization and density change. Our microscopic insights are relevant for understanding how solid-state diffusion changes due to disorder and for building predictive models of operation of materials to be used to encapsulate nuclear waste.
Authors:
; ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)
  2. (United States)
  3. STFC Daresbury Laboratory, Warrington WA4 1EP (United Kingdom)
  4. Steinmann-Institut für Geologie, Mineralogie und Paläontologie, University of Bonn, D-53115 Bonn (Germany)
  5. Institute for High Pressure Physics, RAS, 142190 Moscow (Russian Federation)
Publication Date:
OSTI Identifier:
22402642
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 18; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ACTIVATION ENERGY; AMORPHOUS STATE; CRYSTALS; CURRENTS; DENSITY; DIFFUSION; MOLECULAR DYNAMICS METHOD; OPERATION; RADIOACTIVE WASTES; SIMULATION; SOLIDS; ZIRCONOLITE