STRUCTURE OF LI,NA METAPHOSPHATE GLASSES BY P-31 AND NA-23 MAS-NMR CORRELATED WITH THE MIXED ALKALI EFFECT

被引:78
作者
SATO, RK
KIRKPATRICK, RJ
BROW, RK
机构
[1] UNIV ILLINOIS, DEPT GEOL, 1301 W GREEN ST, URBANA, IL 61801 USA
[2] SANDIA NATL LABS, ALBUQUERQUE, NM 87185 USA
基金
美国国家科学基金会;
关键词
D O I
10.1016/S0022-3093(05)80575-7
中图分类号
TQ174 [陶瓷工业]; TB3 [工程材料学];
学科分类号
0805 ; 080502 ;
摘要
P-31 and Na-23 NMR spectra for glasses along the Li,Na metaphosphate join have been obtained by MAS-NMR spectroscopy. The P-31 results are interpreted in terms of phosphate Q2 (two bridging oxygens) tetrahedra. The P-31 chemical shifts become less shielded (less negative) with increasing [Na]/[Na + Li] ratio. This observation is rationalized in terms of increased paramagnetic deshielding due to increased average electron density in the P-O bonds with increasing [Na]/[Na + Li] ratio. The Na-23 peak maxima also become deshielded with increased [Na]/[Na + Li], suggesting the effects of Li-(non-bridging oxygen)-Na linkages. Both P-31 and Na-23 peaks have greater full-widths at half-height (FWHH) for the intermediate (mixed Li,Na) compositions compared with the Li or Na end-member, reflecting a greater distribution of P and Na sites due to the presence of both Li and Na. The glass transition temperatures have a minimum at [Na]/[Na + Li] = 0.6, thus showing a mixed alkali effect, previously explained by mixed alkali pairs (Li-NBO-Na) detected by the NMR experiments.
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页码:257 / 264
页数:8
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