Dynamics of Na in sodium aluminosilicate glasses and liquids |
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Authors: | A M George J F Stebbins |
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Institution: | 1. Deparment of Geological and Environmental Sciences, Stanford University, 94305-2115, Stanford, CA, USA
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Abstract: | 23Na NMR measurements on Na2Si3O7, Na3AlSi6O15, and NaAlSi3O8 glasses from room temperature to 1200°C show that the dynamics and local structure of sodium in silicate/aluminosilicate glasses and melts vary with composition and temperature.The peak positions decrease in frequency between room temperature and 200°C indicating that the Na sees a larger average site as temperature is increased. Between 200°–300° and 700°C, line widths, nutation frequencies and peak positions are consistent with motional averaging of quadrupolar satellites. Above 700°C there is little or no change in the peak positions with temperature. Chemical shifts of the materials at 1000°C (Na2Si3O7: 3.6; Na3AlSi6O15:-1.3; NaAlSi3O8:-6.4 ppm) indicate a slight change in the average Na coordination number from 6–7 for the silicate to 7–8 for the aluminosilicates. |
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