In Situ Spectroscopy and Spectroelectrochemistry of Uranium in High-Temperature Alkali Chloride Molten Salts

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• 作者：Ilya B. Polovov ; Vladimir A. Volkovich ; John M. Charnock ; Brett Kralj ; Robert G. Lewin ; Hajime Kinoshita ; Iain May ; Clint A. Sharrad
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：September 1, 2008
• 年：2008
• 卷：47
• 期：17
• 页码：7474-7482
• 全文大小：268K
• 年卷期：v.47,no.17(September 1, 2008)
• ISSN：1520-510X

文摘

Soluble uranium chloride species, in the oxidation states of III+, IV+, V+, and VI+, have been chemically generated in high-temperature alkali chloride melts. These reactions were monitored by in situ electronic absorption spectroscopy. In situ X-ray absorption spectroscopy of uranium(VI) in a molten LiCl−KCl eutectic was used to determine the immediate coordination environment about the uranium. The dominant species in the melt was [UO₂Cl₄]²⁻. Further analysis of the extended X-ray absorption fine structure data and Raman spectroscopy of the melts quenched back to room temperature indicated the possibility of ordering beyond the first coordination sphere of [UO₂Cl₄]²⁻. The electrolytic generation of uranium(III) in a molten LiCl−KCl eutectic was also investigated. Anodic dissolution of uranium metal was found to be more efficient at producing uranium(III) in high-temperature melts than the cathodic reduction of uranium(IV). These high-temperature electrolytic processes were studied by in situ electronic absorption spectroelectrochemistry, and we have also developed in situ X-ray absorption spectroelectrochemistry techniques to probe both the uranium oxidation state and the uranium coordination environment in these melts.