Local structure of alkalis in mixed-alkali borate glass to elucidate the origin of mixed-alkali effect
| Autor: | Yuya Takahashi, Hirokazu Masai, Shunichi Kaneko, Yomei Tokuda, Shigeto Fujimura, Toshinobu Yoko, Yoshikatsu Ueda |
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| Rok vydání: | 2015 |
| Předmět: |
010302 applied physics
Mixed-alkali effect Coordination number Sodium Inorganic chemistry Analytical chemistry Clay industries. Ceramics. Glass chemistry.chemical_element Borate glass 02 engineering and technology 021001 nanoscience & nanotechnology Alkali metal 01 natural sciences NMR NMR spectra database TP785-869 chemistry Caesium 0103 physical sciences Ceramics and Composites Cs 0210 nano-technology Spectroscopy Boron |
| Zdroj: | Journal of Asian Ceramic Societies, Vol 3, Iss 4, Pp 412-416 (2015) |
| ISSN: | 2187-0764 |
| DOI: | 10.1016/j.jascer.2015.09.002 |
| Popis: | We report the structural analysis of Na+ and Cs+ in sodium cesium borate crystals and glasses using 23Na and 133Cs magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The composition dependence of NMR spectra of the borate was similar to that of the silicate: (1) the peak position of cesium borate crystals shifted to upfield for structures with larger Cs+ coordination numbers, (2) the MAS NMR spectra of xNa2O-yCs2O-3B2O3 (x = 0, 0.25, 0.5, 0.75, 1.0, x + y = 1) glass showed that the average coordination number (CN) of both the alkali cations decreases with increasing Cs+/(Na+ + Cs+) ratio. However, the degree of decrement in borates is much smaller than that in silicates. We have considered that the small difference in CN is due to 4-coordinated B, because it is electrically compensated by the alkali metal ions resulting in the restriction of having various coordinations of O to alkali metal. |
| Databáze: | OpenAIRE |
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