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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Solid-state NMR and XANES studies of lithium and silver silicate gels synthesized by the sol-gel route
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Solid-state NMR and XANES studies of lithium and silver silicate gels synthesized by the sol-gel route

机译：溶胶-凝胶法合成硅酸锂和硅酸银凝胶的固态NMR和XANES研究

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The objective of this study is to understand the effect of low temperature sol-gel synthesis on the microstructural properties of lithium [xLi(2)O-(1 - x)SiO2; x = 0.1-0.8 in steps of 0.1] and silver [xAg(2)O-(1 - x)SiO2; x = 0.1-0.8 in steps of 0.1] silicate xerogels via solid state nuclear magnetic resonance (NMR) and X-ray absorption near edge structure (XANES) techniques. The Li silicate xerogels were analyzed with solid-state Li-7 and Si-29 NMR and the Ag silicate xerogels were studied with Ag XANES. At high Li loading, Li-7 NMR shows quadrupolar satellite transitions attributed to LiNO3, a phase also found with X-ray diffraction (XRD). At low Li loading, both NMR and XRD results show an amorphous xerogel. The silicate network is monitored with Si-29 NMR and shows evidence of Li incorporation. For the Ag silicate xerogels, Ag-L-III XANES spectral studies show a local environment similar to AgNO3 for low Ag loading levels, and an increased Ag oxidation for higher Ag loading levels. Si K edge spectra show only an amorphous phase, with no evidence of a crystalline quartz phase. The electrical conductivity of the lithium silicates was estimated from impedance data and the highest conductivity is exhibited by the 0.3Li(2)O-0.7SiO(2) composition xerogel. The conductivity dependence on loading level strongly suggests that the observed conductivity is due to Li+ mobility. However, further experimental studies are needed to rule out the possibility that the conductivity is, at least in part, due to H+ mobility. Variation in conductivity is explained qualitatively using existing theoretical models. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 33]
机译：这项研究的目的是了解低温溶胶-凝胶合成对锂[xLi（2）O-（1-x）SiO2; x = 0.1-0.8（以0.1为步长）和银[xAg（2）O-（1- x）SiO2;通过固态核磁共振（NMR）和X射线吸收近边缘结构（XANES）技术，以0.1]硅酸盐干凝胶为步长x = 0.1-0.8。用固态Li-7和Si-29 NMR分析硅酸锂干凝胶，用Ag XANES研究银硅酸干凝胶。在高Li负载下，Li-7 NMR显示归因于LiNO3的四极卫星跃迁，该相也通过X射线衍射（XRD）发现。在低锂负载下，NMR和XRD结果均显示出非晶态干凝胶。用Si-29 NMR监测硅酸盐网络并显示Li结合的证据。对于Ag硅酸盐干凝胶，Ag-L-III XANES光谱研究表明，对于低Ag含量，局部环境类似于AgNO3，而对于高Ag含量，Ag氧化增加。 Si K边缘光谱仅显示非晶相，没有结晶石英相的迹象。硅酸锂的电导率是根据阻抗数据估算的，而最高的电导率是由0.3Li（2）O-0.7SiO（2）组成的干凝胶表现出来的。电导率对负载水平的依赖性强烈表明，观察到的电导率归因于Li +迁移率。然而，需要进一步的实验研究来排除电导率至少部分地由于H +迁移率的可能性。使用现有的理论模型定性地解释了电导率的变化。 （C）2002 Elsevier Science B.V.保留所有权利。 [参考：33]

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