Hydrothermal Method of Preparation of Actinide(IV) Phosphate Hydrogenphosphate Hydrates and Study of Their Conversion into Actinide(IV) Phosphate Diphosphate Solid Solutions

Abstract : Several compositions of Th2-x/2AnIVx/2(PO4)2(HPO4)·H2O (An = U, Np, Pu) were prepared through hydrothermal precipitation from a mixture of nitric solutions containing cations and concentrated phosphoric acid. All the samples were fully characterized by X-ray diffraction, UV-vis, and infrared spectroscopies to check for the existence of thorium-actinide(IV) phosphate hydrogenphosphate hydrates solid solutions. Such compounds were obtained as single phases, up to x = 4 for uranium, x = 2 for neptunium, and x < 4 for plutonium, the cations being fully maintained in the tetravalent oxidation state. In a second step, the samples obtained after heating crystallized precursors at high temperature (1100 C) were characterized. Single-phase thorium-actinide(IV) phosphate-diphosphate solid solutions were obtained up to x = 0.8 for Np(IV) and x = 1.6 for Pu(IV). For higher substitution rates, polyphase systems composed by -TAnPD, An2O(PO4)2, and/or -AnP2O7 were formed. Finally, this hydrothermal route of preparation was applied successfully to the synthesis of an original phosphate-based compound incorporating simultaneously tetravalent uranium, neptunium and plutonium.
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Submitted on : Tuesday, January 22, 2008 - 10:00:54 AM
Last modification on : Tuesday, January 22, 2008 - 10:00:54 AM

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N. Dacheux, S. Grandjean, J. Rousselle, N. Clavier. Hydrothermal Method of Preparation of Actinide(IV) Phosphate Hydrogenphosphate Hydrates and Study of Their Conversion into Actinide(IV) Phosphate Diphosphate Solid Solutions. Inorganic Chemistry, American Chemical Society, 2007, 46, pp.10390-10399. <10.1021/ic701297v>. <in2p3-00211902>

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