ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
We report an application of nuclear magnetic resonance (NMR) spectroscopy to the study of fluorine-doped silicate glass prepared by the modified chemical vapor deposition process, prior to drawing the rod into fibers. The silica contains 1.03-wt. % fluorine, as determined by the calibrated intensity of the 19F NMR spectrum. The isotropic chemical shift of the 19F spectrum shows that fluorine bonds only to silicon; there is no evidence of oxyfluorides. Analysis of the distribution of nuclear dipolar couplings between fluorine nuclei reveals that the relative populations of silicon monofluoride sites [Si(O–)3F] and species having near-neighbor fluorines, such as silicon difluoride sites [Si(O–)2F2], are nearly statistically random. That is, to a good approximation, the fluorine substitutes randomly into the oxygen sites of the silica network. There is no evidence of local clusters of fluorine sites, silicon trifluoride sites [Si(O–)F3], or silicon tetrafluoride (SiF4).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.337675
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