The electronic structures and chemical bonding of selected ternary compounds of the family of A4T7X6 (of U4Re7Si6 –type) intermetallics have been studied by ab initio methods. The calculations for two series: Mg4Rh7P6, Sc4Co7Ge6, Ti4Co7Ge6 and uranium containing U4Re7Si6, U4Ru7Ge6, and U4Ru7As6 show common bonding characteristics pertaining to main T1-X and T2-X interaction (T = transition meta...

— In this paper we describe the use of muffin tin orbital techniques, employed in a variety of approximations, to help understand the band structure and bonding in actinide metals and compounds. Simple methods of assessing bandwidfhs and placings, readily accessible to experimentalists, are reviewed for both metals and compounds and their limitations discussed. Examples from the uranium monopni...

In gamma irradiated aqueous acidic uranium solutions, tetravalent uranium ions are easily oxidized while U(VI) ions remain unchanged. In general, valence change of polyvalent metallic ions during chemical reprocessing of spent nuclear fuel solutions can lead to undesirable effects under the influence of the existing gamma radiations. Consequently, studies on valence stabilization of Uranium ion...

Progress continued on method development for the dissolution of difficult-to-dissolve materials, the automated analysis of plutonium and uranium, the preparation of plutonium materials for the Safeguard Analytical Laboratory Evaluation (SALE) Program, and the analysis of HTGR fuel and SALE uranium materials. The previously developed Teflon-container, metal-shell apparatus was applied to the dis...

We present an X-ray absorption near-edge structure (XANES) study of a series of uranium coordination complexes that possess nearly identical first coordination spheres and geometries in a range of oxidation states from U(III) to U(VI). These compounds were obtained through the activation of small molecules, such as ketones, azides, and carbon dioxide, and upon oxidation of a high-valent U(V)≡O ...

The environmental issues concerning uranium mining and milling have long been paid considerable attention in wide aspects in the world [1–4]. It is well known that the industrial activities of mining and milling of uranium ores can lead to release of a tremendous amount of radioactive pollutants (wastewater and tailings, as representative carrier) that consist typically of U and Th compounds. A...

Single crystals of the new uranium lanthanide oxyselenide compounds UYb2O2Se3 and U2Ln2O4Se3 (Ln1⁄4Pr, Sm, Gd) have been synthesized from an Sb2Se3 flux. The structures have been determined from single-crystal X-ray diffraction data. UYb2O2Se3 is isostructural to UYb2O2S3. The structure comprises layers of edge-sharing YbSe6 octahedra and double layers of disordered (U/Ln)O4Se4 square antiprism...