The conversion of ammonium uranate prepared via sol-gel synthesis into uranium oxides

Schreinemachers, Christian; Leinders, Gregory; Verwerft, Marc; Binnemans, Koen; Cardinaels, Thomas; Modolo, Giuseppe

doi:10.1016/j.net.2019.11.004

Journal Article

FZJ-2019-06845

The conversion of ammonium uranate prepared via sol-gel synthesis into uranium oxides

Schreinemachers, C. (Corresponding author)FZJ* ; Leinders, G. ; Modolo, G.FZJ* ; Verwerft, M. ; Binnemans, K. ; Cardinaels, T.

2020
Hakhoe Sŏul

Nuclear engineering and technology 52(5), 1013 - 1021 (2020) [10.1016/j.net.2019.11.004]

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Please use a persistent id in citations: http://hdl.handle.net/2128/24676 doi:10.1016/j.net.2019.11.004

Abstract: A combination of simultaneous thermal analysis, evolved gas analysis and non-ambient XRD techniques was used to characterise and investigate the conversion reactions of ammonium uranates into uranium oxides. Two solid phases of the ternary system were synthesised under specified conditions. Microspheres prepared by the sol-gel method via internal gelation were identified as , whereas the product of a typical ammonium diuranate precipitation reaction was associated to the composition . The thermal decomposition profile of both compounds in air feature distinct reaction steps towards the conversion to , owing to the successive release of water and ammonia molecules. Both compounds are converted into α- above 550 °C, but the crystallographic transition occurs differently. In compound (ADU) the transformation occurs via the crystalline β-UO3 phase, whereas in compound (microspheres) an amorphous intermediate was observed. The new insights obtained on these uranate systems improve the information base for designing and synthesising minor actinide-containing target materials in future applications.

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