X-RAY ABSORPTION SPECTROSCOPIC STUDIES OF SILICATE-GLASSES AND MINERALS
X-RAY ABSORPTION SPECTROSCOPIC STUDIES OF SILICATE-GLASSES AND MINERALS
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DOI：
10.1007/bf00307604
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发表时间：
1987-01-01
影响因子：
1.4
通讯作者：
PETIAU, J
中科院分区：
文献类型：
--
作者：
CALAS, G;BROWN, GE;PETIAU, J
本文介绍了非晶硅酸盐和矿物的x射线吸收光谱（XAS）研究的一些结果，以表明它们在提供短期和在某些情况下，提供阳离子和阴离子的中期结构和键合信息方面的效用。本文回顾了非晶硅酸盐的EXAFS和XANES研究，目的是说明各种类型的玻璃形成阳离子（包括Si， Al, Na， K, Ca, Ti, Fe， Yb和u）在结构环境中的变化，Al显示在所有检查的铝硅酸盐玻璃中以四面体配位出现，包括过铝成分。弱键的Na和Ca阳离子出现在观察到的配位数（范围从6到7）和距离与分子动力学模拟预测的相似的位置。像Ti这样的元素，形成中等强度的键，在低浓度的硅酸盐玻璃中可能显示出超过第一配位壳的某种顺序。硅酸盐玻璃中微量到微量浓度水平的钇和铀的EXAFS研究提供了这些阳离子环境的独特结构信息。用能带理论或分子轨道理论解释了过渡元素硫化物、第三行四面体氧离子和矿物中氧的k边和XANES。
Selected results ofx-ray absorption spectroscopy(XAS) studies of amorphous silicates and minerals are presented in order to show their utility in providing short-and, in certain cases, medium-range structural and bonding information for cations and anions. EXAFS and XANES studies of amorphous silicates are reviewed with the objective of illustrating variations in structural environments of the various types of glass-forming cations, including Si, Al, Na, K, Ca, Ti, Fe, Yb, and U. Al is shown to occur in tetrahedral coordination in all aluminosilicate glasses examined, including peraluminous compositions. The weakly bonded Na and Ca cations are shown to occur in sites with observed coordination numbers (ranging from 6 to 7) and distances similar to those predicted by molecular dynamics simulations. Elements like Ti, which form bonds of intermediate strength, may show some order beyond the first coordination shell at low concentrations in silicate glasses. EXAFS studies of Yb and U in silicate glasses at trace to minor concentration levels provide unique structural information about the environments of these cations. K-edges and XANES of transition element sulfides, third-row tetrahedral oxyanions, and oxygen in minerals are interpreted in terms of band theory or molecular orbital theory.