Disorder among network-modifier cations in silicate glasses; new constraints from triple-quantum ¹⁷ O NMR

Other| December 01, 1997 Disorder among network-modifier cations in silicate glasses; new constraints from triple-quantum 17 O NMR J. F. Stebbins; J. F. Stebbins Stanford University, Department of Geological and Environmental Sciences, Stanford, CA, United States Search for other works by this author on: GSW Google Scholar J. V. Oglesby; J. V. Oglesby Search for other works by this author on: GSW Google Scholar Z. Xu Z. Xu Search for other works by this author on: GSW Google Scholar American Mineralogist (1997) 82 (11-12): 1116–1124. https://doi.org/10.2138/am-1997-11-1209 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation J. F. Stebbins, J. V. Oglesby, Z. Xu; Disorder among network-modifier cations in silicate glasses; new constraints from triple-quantum 17 O NMR. American Mineralogist 1997;; 82 (11-12): 1116–1124. doi: https://doi.org/10.2138/am-1997-11-1209 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract The state of ordering among network-modifier cations in molten silicates has a potentially large effect on their overall configurational entropy, on free energies of mixing, and on viscosity and diffusivity. Most models of thermodynamic and transport properties assume random mixing, but there is relatively little direct microstructural information to constrain the real extent of this disorder. Two-dimensional 17O NMR can produce spectra that are free of quadrupolar broadening and thus in which peak widths for non-bridging oxygen sites directly reflect the extent of disorder in the local structural environment. In this report, we describe new data from triple-quantum magic-angle-spinning (3QMAS) NMR for a series of barium and calcium silicate glasses. Results are best explained by completely random mixing of Ba and Ca, confirming conventional modeling assumptions. Other recent data show, however, that significant ordering may be present (at least at the temperature of the glass transition) for modifier cations with greater differences in size or charge, and among network-forming cations. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.