Influence of the Electrolysis Conditions and Composition of Electrolytes in the M_(2)WO_(4)-M_(2)W_(2)O_(7)-UO_(2)WO_(4) System (M velence Li, Na, K, Cs) on the Oxygen Coefficient of Uranium Oxide

摘要

The oxygen coefficient (O/U atomic ratio) of the cathodic product prepared by potentiostatic electrolysis of tungstate melts was studied in relation to the electrolyte composition, deposition potential, temperature of electrolysis, and cation of the solvent salt. With increasing temperature, the oxygen coefficient of the cathodic product increases. With shifting the deposition potential toward more negative potentials, with increasing concentration of W_(2)O_(7)~(2-) anions, and with decreasing concentration of UO_(2)WO_(4) in the tungstate electrolytes, uranium oxides with smaller oxygen coefficients are formed. The oxygen coefficient decreases with increasing radius of the salt cation, other conditions being equal. The abnormal behavior of melts based on Li_(2)WO_(4) is probably due to lower activity of O~(2-) anions capable to form strong Li_(3)O~(+) complexes with lithium cations in the melt. The experimental results can be accounted for using the model of the ionic composition of uranyl-containing tungstate melts based on the concepts of complexation and stepwise solvolysis of uranyl ions.