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El Monjid A, Szenknect S, Mesbah A, Hunault MOJY, Menut D, Clavier N, Dacheux N. Incorporation of U(IV) in monazite-cheralite ceramics under oxidizing and inert atmospheres. Dalton Trans 2024; 53:2252-2264. [PMID: 38193888 DOI: 10.1039/d3dt03251e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
This work is the first attempt to prepare Nd1-xCaxUxPO4 monazite-cheralite with 0 < x ≤ 0.1 by a wet chemistry method. This method relies on the precipitation under hydrothermal conditions (T = 110 °C for four days) of the Nd1-xCaxUxPO4·nH2O rhabdophane precursor, followed by its thermal conversion for 6 h at 1100 °C in air or Ar atmosphere. The optimized synthesis protocol led to the incorporation of U and Ca in the rhabdophane structure. After heating at 1100 °C for 6 h in air, single-phase monazite-cheralite samples were obtained. However, α-UP2O7 was identified as a secondary minor phase in the samples heated under Ar atmosphere. The U speciation in the samples converted in an oxidising atmosphere was carefully characterized using synchrotron radiation by combining HERFD-XANES and XRD. These results showed the presence of a minor secondary phase containing hexavalent uranium and phosphate with a stoichiometry of U : P = 0.78. This highly labile uranyl phosphate phase incorporated 21 mol% of the uranium initially precipitated with the rhabdophane precursor. This phase was completely removed by a washing protocol. Thus, single-phase monazite-cheralite was obtained through the wet chemistry route described in this work with a maximum U loading of x = 0.08.
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Affiliation(s)
- Alison El Monjid
- ICSM, Univ. Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols/Cèze, France.
| | - Stéphanie Szenknect
- ICSM, Univ. Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols/Cèze, France.
| | - Adel Mesbah
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626 Villeurbanne, France
| | | | - Denis Menut
- Synchrotron SOLEIL, L'Orme des Merisiers, Départementale 128, 91190 Saint-Aubin, France
| | - Nicolas Clavier
- ICSM, Univ. Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols/Cèze, France.
| | - Nicolas Dacheux
- ICSM, Univ. Montpellier, CNRS, CEA, ENSCM, Site de Marcoule, Bagnols/Cèze, France.
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