Thermal studies on the interaction behavior of ternary nitrate mixtures of UO sub(2)(NO sub(3)) sub(2)[middot]6H sub(2)O-NaNO sub(3)-Sr(NO sub(3)) sub(2) at elevated temperatures

Thermal and X-ray diffraction measurements have been used to study the formation of various nitratocomplexes as intermediates and mixed oxides as end products using different mol ratios of the ternary mixtures of UO sub(2)(NO sub(3)) sub(2)[middot]6H sub(2)O, NaNO sub(3) and Sr(NO sub(3)) sub(2) at high temperatures. These results indicate the interaction of UO sub(2)(NO sub(3)) sub(2)[middot]6H sub(2)O and NaNO sub(3) in equimolar ratio to form sodium uranyl nitrate monohydrate (Na[UO sub(2)(NO sub(3)) sub(3)][middot]H sub(2)O), dimerized sodium uranyl oxynitrate (Na sub(2)[(UO sub(2)NO sub(3)) sub(2)(O) sub(2)]) and sodium diuranate (Na sub(2)U sub(2)O sub(7)). The decomposition temperature of Sr(NO sub(3)) sub(2) decreased by 60 [degrees]C in the presence of in-situ formed Na sub(2)U sub(2)O sub(7). The uranium of Na sub(2)U sub(2)O sub(7) intermediate reacts with Sr(NO sub(3)) sub(2) to form various strontium uranium mixed oxides depending on Sr to U ratio in the initial mixtures. During the interaction of Sr(NO sub(3)) sub(2) with Na sub(2)U sub(2)O sub(7), sodium separates out as amorphous Na sub(2)O in the mixtures, containing Sr to U ratio [> or =, slanted] 1. Na sub(2)O phase is not formed in the uranium rich ternary mixture.