Nuclear magnetic resonance studies of the glasses in the system Na2OB2O3SiO2 |
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Authors: | YH Yun PJ Bray |
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Institution: | Department of Physics, Brown University, Providence, Rhode Island 02912, USA |
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Abstract: | The 11B NMR spectra have been used to study the structure of glasses in the system Na2OB2O3SiO2. The fraction of BO4 units, and the fraction of BO3 units with one or two nonbridging oxygens, are measured and analyzed according to a structural model. The results indicate that: (1) for a sodium oxide to boron oxide ratio of 0.5 or less, the Na+1 ions are attracted primarily by the borate network; therefore, the ternary glasses can be viewed as binary sodium borate glasses diluted by SiO2; (2) when the sodium oxide to boron oxide ratio exceeds 0.5, the additional Na2O results in the formation of BSi4O10]?1 units at the expense of diborate and SiO4 units. In this process, Na+1 ions are still taken up only by the borate network. After all the available SiO4 units are consumed to form BSi4O10]?1 units, additional Na+1 ions are proportionally shared between the borate and silicate networks. |
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