Electrochemical behavior and electronic absorption spectra of uranium trivalent ions in molten LiCl-CsCl mixtures

Nagai, Takayuki  ; Uehara, Akihiro*; Fujii, Toshiyuki*; Sato, Nobuaki*; Yamana, Hajimu*

We investigated the redox reactions and coordination circumstances of uranium ions in molten LiCl-CsCl mixtures by cyclic voltammetry and spectrophotometry. The redox potential of U-U with the CsCl mole fraction of 0.1 to 0.2 was slightly more positive than that in LiCl melt. This potential became more negative than that in LiCl melt with the increase of CsCl mole fraction. The CsCl system showed the most negative potential. Though the averaged alkali cationic radius of the melt increases with the increase of CsCl mole fraction, the redox potential with the low CsCl mole fraction was not proportional to the radius. The result indicates that the Gibb's free energy change of U was not in good correlation with the radius. The electronic absorption spectra of U showed that the intensities of absorption peaks decreased with the increase of CsCl mole fraction. The oscillator strength of the hypersensitive transition decreased with the increase of CsCl mole fraction.