Q(n)-Species Distibution in K2O*SiO2 Glass by 29Si Magic Angle Flipping NMR

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Title: Q(n)-Species Distibution in K2O*SiO2 Glass by 29Si Magic Angle Flipping NMR
Creators: Kaseman, Derrick
Advisor: Grandinetti, Philip
Issue Date: 2011-06
Abstract: Two-dimensional magic angle flipping (MAF) was employed to measure the Q(n)distribution in a 29Si enriched potassium disilicate glass, K2O*SiO2.Relative concentrations of Q(4)= 7.23% +/- 0.339%, Q(3)= 82.97% +/-0.118%, Q(2)= 9.80% +/- 0.660% were obtained. Using the thermodynamic model for Q(n)-species disproportionation these relative concentrations yield an equilibrium constant k3 =0.01029 +/- 0.00084, indicating, as expected, that the Q(n)-species distribution is close to binary in the potassium disilicate glass.A Gaussian distribution of isotropic chemical shifts was observed for each Q(n)-species with mean values of -82.74 +/- 0.03 ppm, -91.32 +/- 0.00 ppm, and -101.67 +/- 0.02 ppm, and standard deviations of 3.27 +/- 0.03 ppm, 4.194 +/- 0.003 ppm, and 5.09 +/- 0.03 for Q(2), Q(3), and Q(4), respectively. Additionally, nuclear shielding anisotropy values of zeta=-85.0 +/- 1.3 ppm, eta= 0.48 +/- 0.02 for Q(2), and zeta= -74.9 +/- 0.2 ppm, eta= 0.030 +/- 0.006 for Q(3) were observed in the potassium disilicate glass.
Embargo: No embargo
Series/Report no.: The Ohio State University. Department of Chemistry Undergraduate Research Theses; 2011
Keywords: NMR
Sponsors: National Science Foundation
URI: http://hdl.handle.net/1811/48961
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