Mechanochemistry of the 5f-elements compounds. 5. Influence of the reaction medium on the mechanochemically induced reduction of UO.

The structure changes and the degree of reduction of UO after mechanoactivation in agate and stainless steel vessels in different media are studied. Clearly expressed reduction of U(IV, VI) oxide, accompanied by oxygen release as a result of mechanochemical activation is observed. The highest degree of reduction is reached when mechanoactivation is performed in suspension with nonpolar organic solvents. The presence of acetaldehyde as a reducing agent did not cause valuable increase of the reduction process. Quantitative evaluation of the mechanochemically induced changes in the crystal structure of UO is done. Decrease of the crystallite sizes of both the UO and the reduced form, provoked by the mechanochemical treatment is observed for all the samples. No other uranium-contained compounds, formed during the mechanoactivation in the different media and mixtures were found. [ABSTRACT FROM AUTHOR]