In situ spectroscopy and spectroelectrochemistry of uranium in high-temperature alkali chloride molten salts.
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 [UO 2Cl 4] (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 [UO 2Cl 4] (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.
Polovov
Ilya B
IB
Department of Rare Metals, Ural State Technical University-UPI, Ekaterinburg 62002, Russia. polovov@dpt.ustu.ru
Volkovich
Vladimir A
VA
Charnock
John M
JM
Kralj
Brett
B
Lewin
Robert G
RG
Kinoshita
Hajime
H
May
Iain
I
Sharrad
Clint A
CA