Effect of cationic composition of electrolytes based on the M2MoO4-M2Mo2O7-UO2MoO4 (M = Li, Na, K, Cs) system on the oxygen factor of the uranium electrolytic oxides

摘要

The effects of the electrolyte composition, deposition potential, temperature, and the salt-solvent cation on the oxygen factor (the [O]/[U] atomic ratio) of uranium oxides obtained by potentiostatic electrolysis , of molybdate melts are studied. It is shown that the oxygen factor of the cathodic product increases with the melt temperature. The shift of the deposition potential toward more electionegative values, an increase in the Mo2O72- ion concentration, and a decrease in the UO2MoO4 concentration favor the cathodic formation of uranium oxides with lower oxygen factors. All other conditions being the same, the oxygen factor decreases with increasing the salt-solvent cation radius. The observed anomalous behavior of the Li2MoO4-based electrolytes can be caused by a lower activity in the melts of the O2- anions that are capable of forming stable complexes Li3O+ with lithium cations. The obtained results can be reasonably explained in terms of the model of ionic composition of the uranyl-containing tungstate melts, which is based on the concept of involvement of the uranyl ions in the complexes' formation and stepwise solvolysis.