Protactinium

Myasoedov, Β. F.; Kirby, H. W.; Тананаев, И. Г.

doi:10.1007/978-94-007-0211-0_4

Cited by 4 publications

(2 citation statements)

References 330 publications

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“…Interestingly, the trihydrides with crystal structures analogous to α-and β-UH 3 were observed also for Pa. The lattice parameters a = 415.0 pm for α-PaH 3 and 664.8 pm for β-PaH 3 are practically identical to the isostructural uranium hydrides [28], implying that the Pa-H distances are very close to 232 pm as found in UH 3 .…”

Section: Other Actinidesmentioning

confidence: 61%

Hydrogen in actinides: electronic and lattice properties

Havela

Legut

Kolorenč³

2023

Rep. Prog. Phys.

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Hydrides of actinides, their magnetic, electronic, transport, and thermodynamic properties are discussed within a general framework of H impact on bonding, characterized by volume expansion, affecting mainly the 5f states, and a charge transfer towards H, which influences mostly the 6d and 7s states. These general mechanisms have diverse impact on individual actinides, depending on the degree of localization of their 5f states. Hydrogenation of uranium yields UH2 and UH3, binary hydrides that are strongly magnetic due to a 5f band narrowing and reduction of the 5f‐6d hybridization. Pu hydrides become magnetic as well, mainly as a result of the stabilization of the magnetic 5f 5 state and elimination of the admixture of the non‐magnetic 5f 6 component. Ab‐initio computational analyses, which for example suggest that the ferromagnetism of β‐UH3 is rather intricate involving two non‐collinear sublattices, are corroborated by spectroscopic studies of sputter‐deposited thin films, yielding a clean surface and offering a variability of compositions. It is found that valence‐band photoelectron spectra cannot be compared directly with the 5f n ground‐state density of states. Being affected by electron correlations in the excited final states, they rather reflect the atomic (n‐1) multiplets. Similar tendencies can be identified also in hydrides of binary and ternary intermetallic compounds. H absorption can be used as a tool for fine tuning of electronic structure around a quantum critical point. A new direction is represented by actinide polyhydrides with a potential for high‐temperature superconductivity.

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Section: Other Actinidesmentioning

confidence: 61%

Hydrogen in actinides: electronic and lattice properties

Havela

Legut

Kolorenč³

2023

Rep. Prog. Phys.

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“…Also, in considering long-term geological repository for spent nuclear fuel, 231 Pa and its shorter-lived daughters (i.e. 227 Ac) will be major contributors to the total radioactivity after 10 5 years [16,17]. Likewise, the shorter-lived isotope, 233 Pa, will be present in the nuclear fuel cycle as an immediate decay product of neptunium-237 ( 237 Np), which can originate from several neutron capture and radioactive decay pathways [18].…”

Section: Introductionmentioning

confidence: 99%

A calculation model for liquid-liquid extraction of protactinium by 2,6-dimethyl-4-heptanol

et al. 2015

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Reprocessing of spent nuclear fuel usually employs the solvent extraction technique to recover fissile material, isolate other valuable radionuclides, recover precious metals, and remove contaminants. Efficient recovery of these species from highly radioactive solutions requires a detailed understanding of reaction conditions and metal speciation that leads to their isolation in pure forms. Due to the complex nature of these systems, identification of ideal reaction conditions for the efficient extraction of specific metals can be challenging. Thus, the development of experimental approaches that have the potential to reduce the number of experiments required to identify ideal conditions are desirable. In this study, a full-factorial experimental design was used to identify the main effects and variable interactions of three chemical parameters on the extraction of protactinium (Pa). Specifically we investigated the main effects of the anion concentration (NO3-, Cl-) extractant concentration, and solution acidity on the overall extraction of protactinium by 2,6-dimethyl-4-heptanol (diisobutylcarbinol; DIBC) from both HCl and HNO3 solutions. Our results indicate that in HCl, the extraction of protactinium was dominated by the solution acidity, while in nitric acid the extraction was strongly effected by the [DIBC]. Based on our results, a mathematical model was derived, that describes the relationship between concentrations of anions, extractant, and solution acidity and the expected values of Pa distribution coefficients in both HCl and HNO3. This study demonstrates the potential to predict the distribution coefficient values, based upon a mathematical model generated by a full-factorial experimental design.

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Prediction of Redox Potentials for Ac, Th, and Pa in Aqueous Solution

Dutra,

Romeu,

Dixon

2024

J. Phys. Chem. A

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Density functional theory in conjunction with small core pseudopotentials and the associated basis sets was used to calculate potentials for multiple redox couples, covering a range of oxidation states for Ac (0 to III), Th (0 to IV), and Pa (0 to V) in aqueous solution. Solvation effects were incorporated using a supermolecule-continuum approach, with 30 water molecules representing two solvation shells, and the COSMO and SMD implicit solvation models. The calculated geometries for Ac(III), Th(IV), and Pa(V) were in reasonable agreement with the available experimental data. Using the COSMO model with the B3LYP functional, the calculated redox potentials were within ±0.2 V from experiment for most redox couples. Several pathways were explored for the Pa(V/IV) redox couple for different forms of Pa(V) and Pa(IV). Most Pa(V/IV) redox couples have very similar potentials, ranging from 0 to −0.4 V up to a pH of 1.4. At pH = 1.4, the potentials shift to values that are more negative than −0.7 V, reflecting the growing unfavorable nature of the redox process at higher pH levels. The calculated values for An(III/II) potentials were consistent with prior estimates and the available experimental data. The predicted redox potentials for An(II/I) were highly negative, as expected. For An(I/0) potentials, Th and Pa exhibited positive values, contrasting with the negative values calculated for Ac. The An +m /An(0) potentials agreed better with the experimental data when using the COSMO solvation model as compared to the SMD model.

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Protactinium

Cited by 4 publications

References 330 publications

Hydrogen in actinides: electronic and lattice properties

Hydrogen in actinides: electronic and lattice properties

A calculation model for liquid-liquid extraction of protactinium by 2,6-dimethyl-4-heptanol

Prediction of Redox Potentials for Ac, Th, and Pa in Aqueous Solution

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