[en] The correlations of isomer shifts in various neptunyl(V and VI) compounds with crystallographic structures were revaluated. A linear correlation between the isomer shifts of neptunyl(VI) compounds and Np-O bond lengths of neptunyl group has been demonstrated. On the other hand, it has been evidenced that the isomer shifts of neptunyl(V) compounds are correlated much stronger with the mean Np-O distances in the crystals than the lengths in neptunyl(V) group. (author)

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[en] The Savannah River Site's HB-Line Facility completed a second neptunium oxide production campaign in which nine (9) additional cans of neptunium oxide were produced and shipped to the Idaho National Laboratory and Oak Ridge National Laboratory in the 9975 shipping container. These additional cans were from a different feed solution than the first fifty (50) cans of neptunium oxide that were previously produced and shipped via a Letter of Amendment to the 9975 Safety Analysis Report for Packaging (SARP) content table. This paper will address the challenges associated with demonstrating the neptunium oxide produced from the additional feed solution was equivalent to the original neptunium oxide and within the content description of the Letter of Amendment.

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[en] Magnetization measurements were performed on NpB₂, NpB₄, and NpB₁₂ over the temperature range 2-1802⁰K. NpB₂ is ferromagnetic below T/sub C/ = 99.5 +--2⁰K; NpB₄ antiferromagnetic below T/sub N/ = 52.5 +--2⁰K. These compounds exhibit approximate Curie-Weiss behavior above their ordering temperatures. The corresponding Pu compounds as well as PuB₆ were found not to exhibit magnetic ordering above 2⁰K. The susceptibility of NpB₁₂ is relatively independent of temperature. Attempts to prepare NpB₆ in the arc furnace were unsuccessful. The ferromagnetism of NpB₂ is apparently itinerant in nature, the moment being unsaturable at 52 kOe and 2⁰K and having magnitude approximately 0.3 μ/sub B/ per Np atom. The very occurrence of magnetism in the compound is somewhat surprising considering the relatively small separation between nearest-neighbor Np atoms in the compound, d/sub Np-Np/ = 3.16 A. (auth)

[en] The NpO₂⁺ ion diagramme of energy levels was calculated in terms of the crystalline field theory. The basic state of the ion is sup(3)Xsub(g4) and sup(3)Σsub(g1) as the crystalline field parameter of the O-M-O complex is below or above approximately 11000 cm^-1, respectively. The results are used to discuss the reported NMR data on the structure and complex formation of NpO₂⁺ and PuO₂⁺ in solutions

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