Impurity characterization and thermal decomposition mechanism of ammonium diuranate during in-situ synthesis of U3O8 using simultaneous TG-DTA-FTIR and PXRD measurements

Current studies describe the application of simultaneous TG-DTA-FTIR technique in the in-situ synthesis of tri uranium octaoxide (U3O8) and impurity characterization of the ammonium diuranate (ADU) matrix. Formation of U3O8 could be due to the decomposition of ADU to uranium trioxide (UO3) and finally to U3O8 by the temperature of 500 °C. Presence of carbon and carbonate could be seen as impurities in the matrix. Carbon content has been determined quantitatively using TG and FTIR techniques and the results are in good agreement. Ammonium nitrate was found as impurity in ammonium diuranate matrix. The PXRD studies confirm the formation of U3O8 as end product during the decomposition of ammonium diuranate. From our studies, it is suggested that ammonium diuranate decomposes to tri uranium octaoxide (U3O8) through evolution of nitrogen, hydrogen and oxygen, and not through ammonia evolution in the literature.