THERMAL-DECOMPOSITION OF URANYL-NITRATE HEXAHYDRATE - A THERMAL-ANALYSIS - MASS-SPECTROMETRY STUDY

TG-DTA-EGA studies have shown that anhydrous uranyl nitrate cannot be obtained by thermal decomposition of uranyl nitrate hexahydrate. Hydro lysis and polymerization of the salt during dehydration resulted in hy droxynitrates which decomposed in multiple steps with the evolution of oxides of nitrogen and water. The extent of hydrolysis depended on th e sample size, heating rate and nature of sample containment. Large sa mples on decomposition at relatively high heating rates showed evoluti on of nitric oxide even above 500-degrees-C. Infrared studies on the r esidues prepared at various temperatures supported the conclusions.