The influence of composition on the local structure around yttrium in quenched silicate melts — Insights from EXAFS
The influence of composition on the local structure around yttrium in quenched silicate melts — Insights from EXAFS
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成分对淬火硅酸盐熔体中钇周围局部结构的影响 â 来自 EXAFS 的见解
DOI：
10.1016/j.chemgeo.2012.09.017
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发表时间：
2013
期刊：
影响因子：
3.9
通讯作者：
Hennet L.
中科院分区：
文献类型：
--
作者：
Simon S;Wilke M;Chernikov R;Klemme S;Hennet L.
用扩展X射线吸收精细结构（EXAFS）谱研究了含5000 ppm Y的硅酸盐和铝硅酸盐玻璃中Y周围的结构环境随熔体组成和聚合反应的变化。所使用的玻璃组合物取自Prowatke和Klemme（2005），铝饱和指数（ASI，Al 2 O3/（Na 2 O + K2 O +CaO）的摩尔比）从0.115变化到0.768。此外，使用了来自CaO-Al 2 O3-SiO2（CAS）系统的一组玻璃组合物，其结构数据来自计算机模拟（Haigis等人，2013--本期）。第一配位壳层的Y-O对关联的结构参数是根据解释大的静态无序和非高斯对分布的类γ分布函数从EXAFS确定的。分析表明，对于Prowatke和Klemme（2005）的组合物，配位数从6增加到8，沿着，平均Y-O距离增加0.13 π。对于CAS-组合物，随着平均Y-O距离增加0.06 π，配位数从6增加到7，沿着。这些参数的变化与Y-O对分布的不对称性和宽度的显著增加有关。由于其尺寸和电荷，6重配位Y将优先键合到聚合物熔体网络的非桥接氧上以形成稳定的构型，对于具有低ASI的较少聚合的熔体也是如此。在ASI值接近1的高度聚合熔体中，Y的6倍配位是不可能的，因为几乎只有桥氧可用。因此，通过增加配位数和Y-O距离来平衡Y周围的桥氧的过度键合，以满足局部电荷平衡要求。
The structural environment around Y in silicate and aluminosilicate glasses containing 5000ppm Y was investigated as a function of melt composition and polymerization using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. The used glass compositions were taken from Prowatke and Klemme (2005) varying in the aluminum saturation index (ASI, molar ratio of Al2O3/(Na2O+K2O+CaO)) from 0.115 to 0.768. Furthermore, a set of glass compositions from the system CaO–Al2O3–SiO2(CAS) was used, for which structural data from computer simulations are available (Haigis et al., 2013--this issue). Structural parameters of the Y–O pair correlation of the first coordination shell were determined from the EXAFS based on a gamma-like distribution function that accounts for the large static disorder and non-Gaussian pair distributions. The analysis shows an increase in the coordination number from 6 to 8, along with an increase of the average Y–O distance by 0.13Å for the composition of Prowatke and Klemme (2005). For the CAS-composition an increase of the coordination number from 6 to 7, along with an increase of the average Y–O distance by 0.06Å is obtained. The change of these parameters is associated with a considerable increase in the asymmetry and width of the Y–O pair distribution. Due to its size and charge, 6-fold coordinated Y will preferentially bond to non-bridging oxygens of the polymeric melt network to form a stable configuration, as is the case for the less polymerized melts with low ASI. In highly polymerized melts with ASI values close to one, 6-fold coordination of Y is not possible because almost only bridging oxygens are available. Consequently, over-bonding of bridging oxygens around Y is counterbalanced by an increase of coordination number and Y–O distance to satisfy local charge balance requirements.
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影响因子：
5
作者：
Farges, F;Brown, GE;Rehr, JJ
通讯作者：
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DOI：
--
发表时间：
2002
期刊：
影响因子：
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作者：
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通讯作者：
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影响因子：
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DOI：
--
发表时间：
1996
期刊：
影响因子：
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作者：
F. Farges;G. Brown;A. Navrotsky;H. Gan;John Rehr
通讯作者：
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影响因子：
3.5
作者：
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通讯作者：
B. Wood;J. Blundy