Defect-mediated self-diffusion in calcium aluminosilicate glasses: A molecular modeling study

Adama Tandia, Nikolay T. Timofeev, John Mauro, K. Deenamma Vargheese

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35 Scopus citations

Abstract

The mechanism of self-diffusion in calcium aluminosilicate glasses is investigated at the atomistic level using molecular dynamics (MD) simulations. We study nine glass compositions having the fixed ratio R = [CaO]/[Al 2O3] = 1 and the concentration of SiO2 varied from 11.8 to 76.5 mol%. The diffusion coefficient is calculated for each composition at different temperatures from 300 to 6000 K in steps of 300 K. The self-diffusivities of the various elements are found to be close to each other in magnitude, signifying the cooperative nature of the atomic movement. Network "defects" such as miscoordinated cations, non-bridging oxygen, and oxygen triclusters are also studied as a function of temperature and composition. We find that the behavior of self-diffusion correlates well with the concentration of network defects. A model of self-diffusion in calcium aluminosilicate glasses is proposed where diffusion is considered as a defect-mediated process resulting from bond-switching reactions at high temperature.

Original languageEnglish (US)
Pages (from-to)1780-1786
Number of pages7
JournalJournal of Non-Crystalline Solids
Volume357
Issue number7
DOIs
StatePublished - Apr 1 2011

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Materials Chemistry

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