扩展X射线吸收精细结构
氧烷
X射线吸收光谱法
锆
X射线吸收精细结构
熔盐
协调数
吸收光谱法
吸收(声学)
材料科学
化学
拉曼光谱
分析化学(期刊)
光谱学
无机化学
离子
量子力学
光学
物理
色谱法
复合材料
有机化学
作者
Timothy Lynch,Nancy Birkner,Matthew Christian,Jacob A. Wrubel,Juliano Schorne‐Pinto,Arjen Van Veelen,John R. Bargar,Theodore M. Besmann,Kyle S. Brinkman,Wilson K. S. Chiu
标识
DOI:10.1021/acs.jpcb.1c07552
摘要
Understanding the local environment of the metal atoms in salt melts is important for modeling the properties of melts and predicting their behavior and thus helping enable the development of technologies such as molten salt reactors and solar-thermal power systems and new approaches to recycling rare-earth metals. Toward that end, we have developed an in situ approach for measuring the coordination of metals in molten salt coupling X-ray absorption spectroscopy (XAS) and Raman spectroscopy. Our approach was demonstrated for two salt mixtures (1.9 and 5 mol % SrCl2 in NaCl, 0.8 and 5 mol % ZrF4 in LiF) at up to 1100 °C. Near-edge (X-ray absorption near-edge structure, XANES) and extended X-ray absorption fine structure (EXAFS) spectra were measured. The EXAFS response was modeled using ab initio FEFF calculations. Strontium's first shell is observed to be coordinated with chlorine (Sr2+-Cl-) and zirconium's first shell is coordinated by fluorine (Zr4+-F-), both having coordination numbers that decrease with increasing temperature. Multiple zirconium complexes are believed to be present in the melt, which may interfere and distort the EXAFS spectra and result in an anomalously low zirconium first shell coordination number. The use of boron nitride (BN) powder as a salt diluent for XAFS measurements was found to not interfere with measurements and thus can be used for investigations of such systems.
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