Characterizing pressure-induced coordination changes in CaAl 2O 4 Glass Using 27Al NMR

Samrat A. Amin, Kurt Leinenweber, Chris J. Benmore, Richard Weber, Jeffery Yarger

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Abstract

27Al NMR is used to quantify coordination changes in CaAl 2O 4 glass pressure cycled to 16 GPa. The structure and coordination environments remain unchanged up to 8 GPa, at which 93% of the recovered glass exists as four-fold Al, whereas the remaining population exists as [5,6]Al. Upon densification, [5,6]Al comprises nearly 30% of observed Al, most likely through the generation of three-coordinated oxygen. Negligible changes are observed for the isotropic chemical shift ( [4]Al ? 78.8 ppm, [5]Al ? 46.3 ppm, [6]Al ? 12.6 ppm) and average quadrupole coupling strengths with pressure. 3QMAS spectra suggest less distortion within the newly formed Al environments in comparison with [4]Al. The chemical shift of [4]Al suggests that the aluminate network remains fully polymerized in glasses quenched from pressures up to 16 GPa.

Original languageEnglish (US)
Pages (from-to)2068-2073
Number of pages6
JournalJournal of Physical Chemistry C
Volume116
Issue number3
DOIs
StatePublished - Jan 26 2012

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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