[en] Fano Effect measurements are the key to direct observation of the Kondo or spin shielding intrinsic to models of electron correlation. The Fano Effect is the observation of spin polarized photoelectron emission from nonmagnetic materials, under chirally selective excitation, such as circularly polarized photons. Below are described three spectrometers, with which Fano Effects measurements have been made. (authors)

[en] Suitable microstructures and homogenous microspheres of actinide compounds are of interest for future nuclear fuel or transmutation target concepts to prevent the generation and dispersal of actinide powder. Sol-gel routes are being investigated as one of the possible solutions for producing these compounds. Preliminary work is described involving internal gelation to synthesize mixed compounds including minor actinides, particularly mixed actinide or mixed actinide-inert element compounds. A parameter study is discussed to highlight the importance of the initial broth composition for obtaining gel microspheres without major defects (cracks, craters, etc.). In particular, conditions are defined to produce gel beads from Zr(IV)/Y(III)/Ce(III) or Zr(IV)/An(III) systems. After gelation, the heat treatment of these microspheres is described for the purpose of better understanding the formation of cracks after calcination and verifying the effective synthesis of an oxide solid-solution. (authors)

[en] We report Fermi surface and magnetic properties of a cubic PuIn₃ grown by the indium flux method. Fermi surfaces detected by the de Haas-van Alphen effect can be well explained by the band calculations assuming itinerant 5f electrons. (authors)

[en] In this work, we have undertaken to follow the evolution of the PuCoGa₅ superconducting behavior as a function of the damages created by self-radiation effects induced from the Pu-decay. It is shown that the critical temperature is particularly sensitive with ageing. Ageing effects on fundamental parameters such as the lattice parameters of the PuCoGa₅ and the electrical resistivity provide some new hints of the unconventional character of the superconductivity in this class of materials. (authors)

[en] Specific heat of Pu doped with Am was studied for several Am concentrations (8-20%) ensuring the delta-Pu fcc structure. The results reveal that the gamma value of the low temperature specific heat is lower than originally assumed (gamma of 35 - 55 mJ/mol K2 can be deduced for Pu-8%Am) and does not increase with the Am-induced lattice expansion. The findings can be taken as an indication of the absence of the Pu-5f states at the Fermi level. (authors)

[en] The hydrolysis chemistry of the tetravalent actinides is discussed based on recent studies with thorium. The coupling of high energy x-ray scattering and single crystal diffraction has provided insight into the structures of the polynuclear complexes formed by hydrolytic reactions of the tetravalent actinides. The success of these experiments with thorium presents many opportunities for the elucidation of the structures and thermodynamic quantities describing the dissolved polynuclear complexes of the heavier actinides. (authors)

[en] X-Ray Absorption Spectroscopy (XAS) and Photoelectron Spectroscopy (PES) have been performed upon highly radioactive samples, particularly Plutonium, at the Advanced Light Source in Berkeley, CA, USA. First results from alpha and delta Plutonium are reported as well as a detailed analysis of sample quality. (authors)

[en] Ab initio calculations using SCF approach for and analysis of results of investigation of the electronic structure of the clusters RAn+:[L]k with rare earths or actinides were carried out for the clusters in solids and liquids. Theoretical results for the electronic structure, radial integrals and energy of X- ray lines are presented for AC ions with unoccupied 5f-shell in the clusters in oxides, chlorides and fluorides environment. Possibility of collapse of nf-shell for the separate clusters and identification of electronic state of ions with unstable nuclei, are discussed, too. (author)

[en] This is an exciting time to be involved in plutonium metallurgical research. Over the past few years, there have been significant advances in our understanding of the fundamental materials science of this unusual metal, particularly in the areas of self-irradiation induced aging of Pu, the equilibrium phase diagram, the homogenization of δ-phase alloys, the crystallography and morphology of the α'-phase resulting from the isothermal martensitic phase transformation, and the phonon dispersion curves, among many others. In addition, tremendous progress has been made, both experimentally and theoretically, in our understanding of the condensed matter physics and chemistry of the actinides, particularly in the area of electronic structure. Although these communities have made substantial progress, many challenges still remain. This brief overview will address a number of important challenges that we face in fully comprehending the metallurgy of Pu with a specific focus on aging and phase transformations. (author)

[en] Microhardness testing and transmission electron microscopy are used to study the effects of long-term service on the aging behavior of a water-quenched U₆ wt.% Nb alloy when subjected to isothermal aging at 200 deg. C. The original α'' phase in the WQ-U₆Nb alloy is found to become partially ordered over 18 years of aging at ambient temperatures, i.e., natural aging, forming a microstructure that is featured by antiphase domain boundaries (APBs). When subsequently aged at 200 deg. C, an ordered phase U₃Nb is precipitated through a nucleation-and-growth mechanism, suppressing spinodal decomposition that occurs when the water-quenched alloy is artificially aged at the same temperature. The different phase transformation paths lead to different microhardness changes during artificial aging: the naturally aged alloy is more slowly hardened, but to a greater microhardness peak value. (authors)