Proton Magnetic Resonance Studies of Polycrystalline Uranium Oxide Hydrates. III. UO42H2O

The broad-line proton magnetic resonance spectrum of polycrystalline samples of the compound formulated empirically as UO42H2O has been investigated in the temperature range 77° to 356°K. Analyses of the absorption line shapes, and their derivatives, at 77° and 257°K, coupled with chemical analysis for peroxide oxygen, show that the compound is essentially the dihydrate of uranyl peroxide, UO2(O2)·2H2O. The sample investigated has about 1/12 of its protons in UOH or UOOH groups of a second component, possibly a hydroperoxide, UO(OH)3(OOH), or hydroxy peroxide, UO(OH)2(O2)·H2O. At temperatures between 125° and 210°K, the absorption of the OH protons in this component undergoes changes which are compatible with self-diffusion. The apparent activation energy for this motion is 2 kcal. The two component formulation of the ``compound'' accounts for most, if not all, of its complex chemical behavior.