Hyperfine Fields of 181Ta in UFe4Al8

The γ–γ Perturbed Angular Correlation technique was used to study the hyperfine interaction of ¹⁸¹Ta at the Hf site(s) in UFe₄Al₈ at room temperature and 12 K. The data at room temperature are well described by two electric field gradients, while at low temperature two combined hyperfine interactions have to be considered, one with the magnetic hyperfine field collinear with the c-axis and another with the magnetic hyperfine field in the basal plane. The results are compared with previous Mössbauer and neutron diffraction experiments and the lattice site of Hf is discussed.

     

On the Paucity of Molecular Actinide Complexes with Unsupported Metal—Metal Bonds: A Comparative Investigation of the Electronic Structure and Metal—Metal Bonding in U2X6 (X: Cl,F, OH,NH2, CH3) Complexes and d‐Block Analogues

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.     

Uranium's Valency in U3S5

U₃S₅ has been prepared by chemical transport reaction and investigated using X-ray powder diffraction, FTIR spectroscopy, electrical resistivity measurements, and X-ray photoelectron spectroscopy. U₃S₅ is a semiconductor with a thermal band gap E_g=78.1(4) meV (298 K<T<50 K), which closes gradually to 3.4(4) meV for T<25 K. Photoelectron spectroscopy on single crystals of U₃S₅ and β-US₂ suggest a mixed valency of uranium in U₃S₅. Physical and structural data are consistent with a mixed-valent model (U³⁺)₂U⁴⁺ (S²⁻)₅. A brief survey of literature data on crystal structure and physical properties of uranium sulfides and selenides is given.     

Spaltmolybdänabtrennung durch Extraktion mit Acetylaceton

Die Abtrennung von Spaltmolybdän aus bestrahlten Uranoxidtargets wird untersucht.

Nach dem Auflösen des Brennstoffes und des Hüllenmaterials (Aluminium) in Salpetersäure wird das Molybdän mit einem Gemisch von Acetylaceton und Tetrachlorkohlenstoff extrahiert. Zur Rückextraktion wird Ammoniaklösung verwendet. Es werden Verteilungskoeffizienten und Trennfaktoren angegeben.     

Evaluation of Treatments to Attain Isotopic Equilibration of Plutonium Preceding the Resin Bead Technique for Mass Spectrometric Assay Analysis of Spent Reactor Fuel

Abstract

Ten chemical treatments are evaluated for the attainment of isotopic equilibration of plutonium prior to its sorption on resin beads for assay of dissolved reactor fuel by isotope-dilution mass spectrometry. The one consistently reliable treatment is reduction to Pu(III) with heated ferrous sulfamate followed by oxidation to Pu(IV) with heated sodium nitrite.     

The Uranyl Cation as a Visible‐Light Photocatalyst for C(sp3)−H Fluorination

The fluorination of unactivated C(sp³)?H bonds remains a desirable and challenging transformation for pharmaceutical, agricultural, and materials scientists. Previous methods for this transformation have used bench‐stable fluorine atom sources; however, many still rely on the use of UV‐active photocatalysts for the requisite high‐energy hydrogen atom abstraction event. Uranyl nitrate hexahydrate is described as a convenient, hydrogen atom abstraction catalyst that can mediate fluorinations of certain alkanes upon activation with visible light.     

Closure temperature of (U-Th)/He system in apatite obtained from natural drillhole samples in the Tarim basin and its geological significance

The apatite(U-Th)/He thermochronometry has been used to study the tectono-thermal evolution of mountains and sedimentary basins for over ten years.The closure temperature of helium is important for the apatite(U-Th)/He thermochronometry and has been widely studied by thermal simulation experiments.In this paper,the apatite He closure temperature was studied by establishing the evolutionary pattern between apatite He ages and apatite burial depth based on examined apatite He ages of natural samples obtained from drillholes in the Tarim basin,China.The study showed that the apatite He closure temperature of natural samples in the Tarim basin is approximately 88±5℃,higher than the result(～75℃) obtained from the thermal simulation experiments.The high He closure temperature resulted from high effective uranium concentration,long-term radiation damage accumulation,and sufficient particle radii.This study is a reevaluation of the conventional apatite He closure temperature and has a great significance in studying the uplifting events in the late period of the basin-mountain tectonic evolution,of which the uplifting time and rates can be determined accurately.