Structure vs. composition:: A solid-state 1H and 29Si NMR study of quenched glasses along the Na2O-SiO2-H2O join
Structure vs. composition:: A solid-state 1H and 29Si NMR study of quenched glasses along the Na2O-SiO2-H2O join
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DOI：
10.1016/j.gca.2004.11.012
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发表时间：
2005-05-01
影响因子：
5
通讯作者：
Lee, SK
中科院分区：
文献类型：
--
作者：
Cody, GD;Mysen, BO;Lee, SK
用Si-29单脉冲魔角旋转(SP)核磁共振(MAS)谱、H-1-Si-29交叉极化(CP)MAS核磁共振和快速MAS H-1-核磁共振(FAST MAS)分析了六种水合硅酸盐玻璃(7wt.%H2O)的组成。从Si-29 SPMAS数据中观察到，在低钠组分时，溶解水显着解聚硅酸盐网络。然而，在较高的钠含量下，溶解的H2O并不影响解聚反应的显著增加，而不是仅基于Na/Si比率预测的解聚反应。快速的MAS H-1-核磁共振数据显示，在所研究的每一种玻璃中，质子环境都相当复杂。最高钠浓度玻璃的快速MAS 1H-核磁共振谱没有显示出明显高于低钠浓度玻璃的溶解水分子H2O的证据，这要求在高钠含量下聚合反应的减少涉及钠溶液机理的改变。可变接触时间H-1-Si-29交叉极化(CP)的MAS核磁共振数据表明，随着钠含量的增加，不同Q(N)物种的旋转框架自旋晶格驰豫速率常数(T-1Rho*)增大，这与H-1-Si-29的平均耦合强度降低相关。然而，在最高的钠浓度下，T-1 Rho*显著下降，这与Na2O溶液机理的变化一致。版权所有(C)2005爱思唯尔有限公司。
A suite of six hydrous (7 wt.% H2O) sodium silicate glasses spanning sodium octasilicate to sodium disilicate in composition were analyzed using Si-29 single pulse (SP) magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, H-1-Si-29 cross polarization (CP) MAS NMR, and fast MAS H-1-NMR. From the Si-29 SPMAS data it is observed that at low sodium compositions dissolved water significantly depolymerizes the silicate network. At higher sodium contents, however, dissolved H2O does not affect a significant increase in depolymerization over that predicted based on the Na/Si ratio alone. The fast MAS H-1-NMR data reveal considerable complexity in proton environments in each of the glasses studied. The fast MAS 1H-NMR spectra of the highest sodium concentration glasses do not exhibit evidence of signficantly greater fractions of dissolved water as molecular H2O than the lower sodium concentration glasses requiring that the decrease in polymerization at high sodium contents involves a change in sodium solution mechanism. Variable contact time H-1-Si-29 cross polarization (CP) MAS NMR data reveal an increase in the rotating frame spin lattice relaxation rate constant (T-1 rho*) for various Q(n) species with increasing sodium content that correlates with a reduction in the average H-1-Si-29 coupling strength. At the highest sodium concentration, however, T-1 rho* drops significantly, consistent with a change in the Na2O solution mechanism. Copyright (c) 2005 Elsevier Ltd.