[en] The preparation is described of the ternary oxides formed by hexavalent americium with potassium, rubidium and cesium oxides. The compounds were characterized by X-ray diffraction data. (U.K.)

[en] The absorption spectrum of ErCl₃ (AlCl₃)/sub x/ vapor complex was measured and analyzed using the Judd-Ofelt theory. Structural correlations in other AlCl₃ vapor complexes and radiation emission are discussed. Fluorescence of TbCl₃ (AlCl₃)/sub x/ vapor complex and in the NdCl₃ (AlCl₃)/sub x/ system were studied

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[en] Cesium diuranate, Cs₂U₂O₇, was reacted with 1 mol dm^-3 HCl in a solution calorimeter. The enthalpy of reaction, -(46087 +-102) calsub(th) mol^-1, leads to a standard enthalpy of formation, ΔHsub(f)sup(0)(Cs₂U₂O₇, c, 298.15K), of -(754.3+-1.6)kcalsub(th) mol^-1. Thermodynamics of the Cs + U + O and Rb + U + O systems are discussed with particular emphasis on the formation of cesium and rubidium uranates and diuranates in nuclear reactor fuel. Formation of the monouranates is expected to predominate, although diuranates are also predicted to form, but in rather low concentrations. (author)

[en] Solution and drop-calorimetric studies of magnesium uranate are described. From the solution experiments, the standard enthalpy of formation, Δ Hsub(f)⁰(MgUO₄, c, 298.15 K) was found to be -(1857.0 +- 1.3) kJ mol^-1. The drop-calorimetric experiments gave values for the enthalpy increment [H⁰(T) - H⁰(298.15 K)] and heat capacity Csub(p)⁰(T), which, over the temperature range 298.15 to 1400 K, are best represented by the equations: [H⁰(T) - H⁰(298.15 K)]/J mol^-1 = 110.268(T/K) + 3.3398 x 10^-2(T/K)² - 7.8127 x 10^-6(T/K)³ - 35638; Csub(p)⁰(T)/J K^-1mol^-1 = 110.268 + 6.6796 x 10^-2(T/K) - 2.3438 x 10^-5(T/K)². The complete thermodynamic functions of MgUO₄ are tabulated from 298.15 to 1400 K. The spontaneity of the decomposition of BeUO₄ to its component oxides is advanced as an explanation for the non-existence of this compound. (author)

[en] X-ray photoemission spectroscopy (XPS) measurements are reported for a series of uranyl compounds in which the primary uranium--oxygen (U--O/sub I/) separation varies substantially. Crystal field splittings of the U 6p₃/₂ core electron energy levels were observed. These splittings are explained with the point charge crystal field model when both first and second near uranium neighbors are considered. The systematics of charge migration (observed by monitoring electron core level shifts) associated with bonding in the uranyl series were also investigated. Core level shifts for compounds with different U--O/sub I/ separations are large, but essentially no relative shifts of uranium and oxygen core levels were observed within the uranyl group. Thus charge appears to flow between the uranyl group (as a unit), and the secondary uranium ligands as U--O/sub I/ is varied. The U 5f electron participation in covalent bonding was also studied by systematically measuring XPS line intensities; U 5f electron occupation appears to be minimal. (auth)

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No abstract available