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Kuzenkova AS, Plakhova TV, Nevolin IM, Kulikova ES, Trigub AL, Yapaskurt VO, Shaulskaya MD, Tsymbarenko DM, Romanchuk AY, Kalmykov SN. Formation of Neptunium(V) Carbonates: Examining the Forceful Influence of Alkali and Alkaline Earth Cations. Inorg Chem 2023; 62:21025-21035. [PMID: 38091513 DOI: 10.1021/acs.inorgchem.3c02737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2023]
Abstract
Herein, neptunium(V) carbonates containing sodium or potassium cations were synthesized via chemical precipitation. Various techniques such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetry combined with differential scanning calorimetry, X-ray diffraction, and X-ray absorption spectroscopy were used to analyze the microstructures and elemental compositions of these samples. The crystal structures of hydrated NaNpO2CO3·3H2O (P1, a = 4.3420(2) Å, b = 4.8962(2) Å, c = 10.0933(11) Å, α = 91.014(7)°, β = 77.834(11)°, and γ = 90.004(10)°) and KNpO2CO3 (P63/mmc, a = b = 5.0994(2) Å, c = 10.2210(15) Å) were determined for the first time using the Rietveld method. The synthesized carbonates exhibited distinct structural features and decomposition behaviors, as demonstrated through thermogravimetry analysis, which revealed the presence of crystalline hydrate water in sodium neptunium(V) carbonate. Furthermore, calcium-containing neptunium(V) carbonates were synthesized and characterized. Samples with the general composition Ca0.5NpO2CO3 were obtained using the ion exchange method and chemical precipitation from solutions containing competing cations (Ca2+, Na+, K+, and Mg2+). The synthesis conditions notably affected the diffraction patterns of the obtained calcium neptunium(V) carbonates. This investigation enhances our understanding of the structural properties and thermodynamic stability of neptunium(V) carbonates in the presence of diverse cations commonly found under radioactive waste disposal conditions.
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Affiliation(s)
| | - Tatiana V Plakhova
- Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia
| | - Iurii M Nevolin
- Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninsky Prospect 31 Bld. 4, 119071 Moscow, Russia
| | - Elizaveta S Kulikova
- National Research Centre ⟨⟨Kurchatov Institute⟩⟩, Akademika Kurchatova pl. 1, 123182 Moscow, Russia
| | - Alexander L Trigub
- Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia
- National Research Centre ⟨⟨Kurchatov Institute⟩⟩, Akademika Kurchatova pl. 1, 123182 Moscow, Russia
| | | | - Maria D Shaulskaya
- Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia
| | | | - Anna Yu Romanchuk
- Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia
| | - Stepan N Kalmykov
- Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia
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