The bonding environment of chlorine in silicate melts
The bonding environment of chlorine in silicate melts
复制标题
硅酸盐熔体中氯的结合环境
DOI：
10.1016/j.chemgeo.2022.121269
复制
发表时间：
2023
期刊：
影响因子：
3.9
通讯作者：
Thomas R
中科院分区：
文献类型：
--
作者：
Thomas R
硅酸盐熔体中氯的局部键合环境对熔体的热力学性质和结构有深远的影响，影响熔体的粘度、流变性和挥发脱气潜力。为了限制天然硅酸盐熔体中氯的键合环境，我们测定了44个实验制备的硅酸盐玻璃的X射线吸收近边结构(XANES)和扩展X射线吸收精细结构(EXAFS)区的ClK边X射线吸收精细结构(XAFS)谱。在前缘区域，前缘峰的存在表明氯与硅的共价键。二价阳离子的加入抑制了这一前缘特征，其质心向更高的能量移动，表明改变为越来越多的离子键。在XANES区，主吸收边能量E_0和最大强度能量E_(Max)也与组成有关。富SiO_2玻璃的E0和Emax值相对较低，而2+离子的加入使这两个值都增加到接近端元氯化物CaCl2、MgCl2和FeCl2中的值。在两个富钠玻璃中，E_0和E_(Max)在氯化钠中接近相应的能量。因此，玻璃中的成键似乎与简单氯化物中的成键密切相关。这可能是由于团簇在熔体本身或玻璃中由于淬火过程中的重排而产生Casingle键、MgSingle键、Fesingle键和Nasingle键，EXAFS部分玻璃光谱证实了XANES区域的结论。为了确定光谱是否依赖于压力、温度或合成的氯逸度，使用单一起始组成(不含铁的单斜辉石，An50Di28Fo22)进行了9个实验，范围包括温度(1300-1400kbar)、压力(5-20kbar)、氯逸度(f(Cl2))(1.38E−03至1.66E−06)和水含量(预期为0-8wt%H2O)。结果表明，XANES和EXAFS区域的光谱几乎没有变化，这表明氯键与实验参数无关，或者所有熔体都猝灭了具有相同氯原子周围局域结构的玻璃。
The local bonding environment of chlorine in silicate melts has a profound influence over the thermodynamic properties and structure of a melt, affecting the viscosity, rheology, and volatile degassing potential. To constrain the bonding environment of Cl in natural silicate melts, we have determined Cl K-edge X-ray absorption fine structure (XAFS) spectra for 44 experimentally produced silicate glasses in both the X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) regions. In the pre-edge region, the presence of a pre-edge peak indicates covalent bonding of chlorine with silicon. Addition of divalent cations suppresses this pre-edge feature, and its centroid shifts to higher energy, indicating a change to increasingly more ionic bonding. In the XANES region the main absorption edge energy, E0, and the energy of maximum intensity, EMax, are also compositionally dependent. SiO2- rich glasses have relatively low values of E0and EMaxwhile the addition of 2+ions increases both to values close to those found in the end-member chlorides CaCl2,MgCl2,and FeCl2. In two Na-rich glasses, E0and EMaxare close to corresponding energies in NaCl. It appears, therefore that bonding in the glasses is closely related to that found in the simple chlorides. This may be due to clustering which generates Casingle bondCl, Mgsingle bondCl, Fesingle bondCl and Nasingle bondCl linkages either in the melts themselves or in the glasses due to rearrangements during quenching.The EXAFS parts of the glass spectra confirm the conclusions derived from the XANES region. These show that, as expected from the XANES region, addition of Ca and Fe2+leads to R-space peaks which are closely related to those found in anhydrous CaCl2and FeCl2respectively.In order to determine if the spectra depend on pressure, temperature or chlorine fugacity of synthesis, 9 experiments were conducted using a single starting composition (Fe-free haplobasalt, An50Di28Fo22) across a range of temperatures (1300–1400 °C), pressures (5–20 kbar), chlorine fugacities (f(Cl2)) (1.38E−03to 1.66E−06), and water contents (expected 0–8 wt% H2O). The results show that there is almost no change in the spectra across the XANES and EXAFS regions, indicating either that chlorine bonding is independent of the intensive parameters of the experiment or that all melts quench to glasses with the same local structure around the Cl atoms.
登录
查看更多内容
氯 K 边 X 射线吸收光谱作为氯-锰键合探针：与光系统 II 中的放氧复合物相关的模型系统 †
DOI：
--
发表时间：
1997
期刊：
影响因子：
--
作者：
A. Rompel;J. Andrews;R. M. Cinco;M. Wemple;G. Christou;N. A. Law;V. Pecoraro;K. Sauer;V. Yachandra;M. Klein
通讯作者：
M. Klein
成分对硅酸盐熔体中氯溶解度和行为的影响
DOI：
10.2138/am-2022-8450
发表时间：
2023
期刊：
Journal of Earth and Planetary Materials
影响因子：
--
作者：
Thomas R
通讯作者：
Thomas R
影响因子：
3.9
作者：
A. Baasner;B. Schmidt;S. Webb
通讯作者：
A. Baasner;B. Schmidt;S. Webb
影响因子：
3.1
作者：
J. Stebbins;L. Du
通讯作者：
L. Du
氯浸渍二氧化硅中的 SiCl 基团
DOI：
--
发表时间：
1996
期刊：
影响因子：
--
作者：
A. Chmel;V. Svetlov
通讯作者：
V. Svetlov