Thermal Stability and Products of Decomposition of Hydroxylaminate Uranyl Complexes

The thermal behavior of hydroxylaminate uranyl complexes [UO2(NH2O)2(H2O)2] ‧ H2O, [UO2(NH2O)2], and [UO2(i-C3H7NHO)2(H2O)2] ‧ 2H2O has been studied. The complexes decompose at a low temperature (<200°C) resulting in nanoscale powders of uranium dioxide. The composition of solid decomposition products for each complex has been determined by powder X-ray diffraction. For the complex with isopropylhydroxylamine, the composition of the gaseous decomposition products has been determined. Schemes of redox reactions, which can take place during the thermal decomposition of the complexes, are proposed. It has been suggested that the redox reactions are dependent on the substituents at the nitrogen atom of the hydroxylaminate ligands.