Dense hydrous magnesium silicates, phase D, and superhydrous B: New structural constraints from one- and two-dimensional 29 Si and 1H NMR

Xianyu Xue, Masami Kanzaki, Anton Shatskiy

    Research output: Contribution to journalArticlepeer-review

    28 Citations (Scopus)

    Abstract

    To gain new structural insights into phase D and superhydrous B, two phases of potential mantle water reservoir, we have applied a range of one- (1D) and two-dimensional (2D) 1H and 29Si NMR techniques, as well as Raman spectroscopy, to samples synthesized at 24 GPa and 900-1100 °C. These data have revealed that phase D is characterized by disordered and varying local structures around both Si and H. The 29Si NMR spectra of phase D contain a nearly symmetric, broad peak near-177.7 ppm, attributable to octahedral Si with local structural disorder. The high-resolution 1H CRAMPS spectra of phase D contain a main broad peak near 12.6 ppm with shoulders near 10 and 7 ppm, suggesting a distribution of hydrogen bonding distances. For superhydrous B, our comprehensive 2D 1H and 29Si NMR results have clearly revealed that it contains dissimilar (H1-H2) pairs and one tetrahedral Si site, consistent with space group Pnn2.

    Original languageEnglish
    Pages (from-to)1099-1111
    Number of pages13
    JournalAmerican Mineralogist
    Volume93
    Issue number7
    DOIs
    Publication statusPublished - Jul 2008

    Keywords

    • NMR
    • Order/disorder
    • Phase D
    • Raman
    • Space group
    • Superhydrous B

    ASJC Scopus subject areas

    • Geophysics
    • Geochemistry and Petrology

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