Summary and Comparison of Properties of the Actinide and Transactinide Elements

Edelstein, Norman M.; Fuger, J.; Katz, Joseph; Morss, Lester R.

doi:10.1007/978-94-007-0211-0_15

Cited by 57 publications

(91 citation statements)

References 106 publications

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“…As noted in Section 2, the californium oxide is in a palladium matrix and the cermet wire is doubly encapsulated. Cf 2 O 3 has reported densities of 11.39 to 12.69 g/cm 3 [29] which are similar to the density of Pd. With Pd representing 99.9% of the cermet wire, Pd density is adopted for the Pd-Cf 2 O 3 mixture.…”

Section: Mcnp Modeling Of the Irradiatorsupporting

confidence: 52%

Design, Construction, and Modeling of a²⁵²Cf Neutron Irradiator

Anderson

Holbert

Bowler

2016

Science and Technology of Nuclear Installations

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Neutron production methods are an integral part of research and analysis for an array of applications. This paper examines methods of neutron production, and the advantages of constructing a radioisotopic neutron irradiator assembly using252Cf. Characteristic neutron behavior and cost-benefit comparative analysis between alternative modes of neutron production are also examined. The irradiator is described from initial conception to the finished design. MCNP modeling shows a total neutron flux of 3 × 105 n/(cm2·s) in the irradiation chamber for a 25 μg source. Measurements of the gamma-ray and neutron dose rates near the external surface of the irradiator assembly are 120 μGy/h and 30 μSv/h, respectively, during irradiation. At completion of the project, total material, and labor costs remained below $50,000.

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Section: Mcnp Modeling Of the Irradiatorsupporting

confidence: 52%

Design, Construction, and Modeling of a²⁵²Cf Neutron Irradiator

Anderson

Holbert

Bowler

2016

Science and Technology of Nuclear Installations

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“…Importantly, selectivity for Nd 3+ is most desired, since this ion is often used as an analogue for Am 3+ , and shares similar physical and chemical properties with other lanthanides and actinides. 47 The relationship between Nd 3+ and Am 3+ uptake is explored further by experimentation below.…”

Section: Resultsmentioning

confidence: 99%

Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework

Demir¹,

Brune²,

Humbeck³

et al. 2016

ACS Cent. Sci.

111

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Porous aromatic frameworks (PAFs) incorporating a high concentration of acid functional groups possess characteristics that are promising for use in separating lanthanide and actinide metal ions, as required in the treatment of radioactive waste. These materials have been shown to be indefinitely stable to concentrated acids and bases, potentially allowing for multiple adsorption/stripping cycles. Additionally, the PAFs combine exceptional features from MOFs and inorganic/activated carbons giving rise to tunable pore surfaces and maximum chemical stability. Herein, we present a study of the adsorption of selected metal ions, Sr2+, Fe3+, Nd3+, and Am3+, from aqueous solutions employing a carbon-based porous aromatic framework, BPP-7 (Berkeley Porous Polymer-7). This material displays high metal loading capacities together with excellent adsorption selectivity for neodymium over strontium based on Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. Based in part upon X-ray absorption spectroscopy studies, the stronger adsorption of neodymium is attributed to multiple metal ion and binding site interactions resulting from the densely functionalized and highly interpenetrated structure of BPP-7. Recyclability and combustibility experiments demonstrate that multiple adsorption/stripping cycles can be completed with minimal degradation of the polymer adsorption capacity.

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“…[14,[16][17][18][19][20] In addition, two neptunium complexes were shown to display slow relaxation of the magnetization. [26,27] With decreasing temperature, c T decreases monotonically and reaches values of c T = 0.62, 0.27, and 0.50 cm 3 K mol À1 , at 1.8 K for 1-3, respectively. SMM behavior in all published examples is much more pronounced in an external field than in zero field, which suggests that quantum tunneling of the magnetization plays a significant role in shortening the relaxation times.…”

mentioning

confidence: 97%

The Inherent Single‐Molecule Magnet Character of Trivalent Uranium

et al. 2013

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Single-molecule magnets (SMMs) are molecules that exhibit slow relaxation of their magnetization of purely molecular origin. [1] This is because SMMs possess high-spin ground states in which spin-orbit coupling results in zero-field splitting of the (2S + 1)-fold degenerate ground multiplet, which in turn creates a thermal barrier to relaxation of the magnetization that gives rise to magnetic bistability. SMMs form part of a larger family of molecular nanomagnets which are the subject of intense research because of their potential applications in fields as diverse as molecule-based information storage, [1] quantum information processing, [2] spintronics, [3] and magnetocaloric refrigeration. [4] SMMs are often based on transition-metal clusters, but significant attention has recently focused on complexes of single and multiple lanthanoid ions, because the crystal-field splitting of the lowest Russell-Saunders multiplet engenders large magnetic anisotropies. [5][6][7][8][9][10][11] These anisotropies are responsible for high relaxation barriers and therefore slow magnetic relaxation. However, well isolated high-spin ground states are difficult to achieve within polynuclear lanthanoid SMMs because the valence 4f orbitals have limited radial extension and are usually energetically incompatible with ligand orbitals. These inherent 4f orbital properties give predominantly ionic interactions and results in weak magnetic exchange coupling with neighboring spin centers, with very few exceptions. [7,12] In principle, actinoids, and in particular uranium, possess properties that render these ions ideal candidates from which to construct SMMs. This is because, compared to the lanthanoids, uranium exhibits enhanced crystal field splitting, [13,14] as well as increased covalency, the latter enabling significant spin couplings in polynuclear systems, [15] and therefore both stronger magnetic exchange and anisotropies can be envisaged. This premise was realized recently with reports of several closely related single-ion pyrazolylborate uranium(III) complexes which were shown to display SMM behavior. [14,[16][17][18][19][20] In addition, two neptunium complexes were shown to display slow relaxation of the magnetization. [15,21] The fact that all uranium(III) SMMs reported to date are closely related to each other raises the question as to how sensitive SMM behavior in trivalent uranium is to the composition of the coordination sphere and its symmetry. SMM behavior in all published examples is much more pronounced in an external field than in zero field, which suggests that quantum tunneling of the magnetization plays a significant role in shortening the relaxation times. However, in principle, low-symmetry crystal field components cannot induce tunneling of the magnetization, because uranium(III) is a Kramers half-integer angular momentum ion. Also the nuclear spin I = 0 of 238 U cannot induce tunneling of the magnetization. The answer to the question of what causes efficient quantum tunneling will have serious implications for ...

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Summary and Comparison of Properties of the Actinide and Transactinide Elements

Cited by 57 publications

References 106 publications

Design, Construction, and Modeling of a²⁵²Cf Neutron Irradiator

Design, Construction, and Modeling of a²⁵²Cf Neutron Irradiator

Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework

The Inherent Single‐Molecule Magnet Character of Trivalent Uranium

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Summary and Comparison of Properties of the Actinide and Transactinide Elements

Cited by 57 publications

References 106 publications

Design, Construction, and Modeling of a252Cf Neutron Irradiator

Design, Construction, and Modeling of a252Cf Neutron Irradiator

Extraction of Lanthanide and Actinide Ions from Aqueous Mixtures Using a Carboxylic Acid-Functionalized Porous Aromatic Framework

The Inherent Single‐Molecule Magnet Character of Trivalent Uranium

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Design, Construction, and Modeling of a²⁵²Cf Neutron Irradiator

Design, Construction, and Modeling of a²⁵²Cf Neutron Irradiator