The hydrothermal reaction of Th(NO3)4·xH2O with I2O5 in the presence of KCl results in the crystallization of α-Th(IO3)4(H2O) and β-Th(IO3)4(H2O). The structure of αTh(IO3)4(H2O) is three-dimensional and contains Th4+ cations bound by iodate anions and a coordinating water, creating a tricapped trigonal prismatic environment around the thorium centers. βTh(IO3)4(H2O) is layered, and contains ThO9 units that are best described as capped square antiprisms. Crystallographic data: (193 K, MoKα, λ = 0.71073 Å): α-Th(IO3)4(H2O), monoclinic, space group P21/c, a = 7.2335(3) Å, b = 24.6046(12) Å, c = 7.0150(3) Å, b = 112.1888(8)°, V = 1156.05(9), Z = 4, R(F) = 1.97%; βTh(IO3)4(H2O), monoclinic, space group C2/c, a = 33.928(1) Å, b = 5.7466(2) Å, c = 12.4509(5) Å, b = 107.9896(7)°, V = 2308.8(1), Z = 8, R(F) = 1.63%.

Batch adsorption/dissolution experiments were conducted to examine the interactions between 233U(VI) and a synthetic aluminum oxyhydroxide (boehmite, γ-AlOOH) in 1.0M NaCl suspensions containing 1-hydroxyethane-1,1-diphosphonic acid (HEDPA). In the pH range 4 to 9, complexation of Al(III) by HEDPA significantly enhanced dissolution of boehmite. This phenomenon was especially pronounced in the neutral pH region where the solubility of aluminum, in the absence of complexants, is limited by the formation of sparsely soluble aluminum hydroxides. At high pH levels, dissolution of synthetic boehmite was inhibited by HEDPA, likely due to sorption of Al(III)/HEDPA complexes. Addition of HEDPA to equilibrated U(VI)-synthetic boehmite suspensions yielded an increase in the aqueous phase uranium concentration. The concentration of uranium continually increased over 59 days. Partitioning of uranium between the solid and aqueous phase was found to correlate well with HEDPA partitioning.

General understanding of intramolecular interactions engaged in molecular actinide species, in other words physical chemical mechanisms that drive the affinity of chelating ligands for actinide cations still needs to be deepened. In this field, X ray Absorption Spectroscopy has been extensively used as a structural and electronic metal cation probe. Combination with more traditional spectroscopic techniques as spectrophotometry is an ideal tool for the understanding of the chelation mechanism. Metallobiomolecules are considered as elaborate inorganic complexes with well-designed metal active sites. Although the various interaction processes between essential cations to biology and proteins are widely studied, focus on the actinide family is more seldom. Actinide impact to biological cycles has been motivated by risk assessments related to the wide use of nuclear fuel sources and industrial or military applications. In particular, the interactions of these cations with the biologically active complexation sites are only partially understood.

We calculated the Knight shift and spin-lattice relaxation rates of Pu-115 compounds assuming d-wave superconductivity in the presence of strong impurity scattering. We discuss the implications for recent measurements of the spin-lattice relaxation rate in the Pu-115 compound PuRhGa5 by Sakai and coworkers [J. Phys. Soc. Jpn. 74, 1710 (2005)] and present a prediction for the corresponding Knight shift. In addition, we noticed a significant round-off of the spin-lattice relaxation rate 1/T1 just above the superconducting transition temperature that is not observed in the sister compound PuCoGa5. It appears that in PuRhGa5 superconductivity is mediated by spin fluctuations, too. This provides additional support to the scenario of superconducting pairing mediated by spin fluctuations in the Pu-115 compounds similar to the Ce-115 compounds and the high-temperature copper-oxide superconductors.

Predicting the behaviour of radioactive wastes can be facilitated by comparison with the evolution of natural groundwater systems. During a study of the Kanamaru U mineralization (Japan), geochemical approaches for understanding a shallow (0-50 m) fresh groundwater flow system are being assessed. Deep granitic waters are Ca-HCO3-dominated and slightly acidic to slightly alkaline. Shallow waters within sediments display lower pH and they are more dilute. Halide concentrations suggest the existence of a non marine Br-rich and Cl-depleted deep groundwater in the basement. 234U/238U and 230Th/234U activity ratios in the mineralized sedimentary rocks indicate that U mobilization took place within the last 350,000 years. U dissolution currently continues and it is controled by lateral groundwater flow whereas vertical diffusion appears negligible. Dissolved alkaline earths concentrations and the 87Sr/86Sr ratio indicate that solutes exchanges take place through uppermost low permeable granite followed by mixing with more dilute and Cl-type shallow groundwater.

Uranyl-organic complexation in geologic fluids can have a profound impact upon uranium solubility and transport. Studies of uranyl organometallic crystal structures provide a basis for understanding complexation of the uranyl ion in solution.

The crystal structures of several novel uranyl oxalates, synthesized under mild hydrothermal conditions, have been determined. These structures demonstrate new features little seen or not previously known in this chemical system, in particular polymerization into infinite sheets and direct linkage of uranyl polyhedra. Further work on the chemistry of this and other systems of hexavalent uranium and low molecular weight carboxylic acids, especially formic acid, is likely to turn up new insights.

Although a hierarchical scheme exists for classifying inorganic uranyl compounds [1], no similar work has been done for organic compounds. Such a hierarchy would have practical benefits, in particular making structural information more accessible and understandable to workers studying related problems such as the environmental transport of hexavalent uranium as dissolved organic complexes. We offer a simple scheme that classifies uranyl oxalate structures by analyzing the long-range structural features and the coordination environments of uranyl ions, which leads to a structural symbol that can be used to easily identify uranyl oxalates with common structural features. This system is equally applicable to other carboxylate complexes with the uranyl ion, and could be extended to apply to any organic complex of the uranyl ion.

X-ray absorption near edge structure (XANES) is a sensitive probe of the electronic structure, and can provide information about the valency, the unoccupied electronic states and the effective charge of the absorbing atom. In this paper, near edge x-ray absorption fine structure spectra are reported at the L3, M5 and N5 thresholds and used to determined structural and electronic properties of U(VI) within uranyl nitrate (UO2(NO3)2.6H2O) and perovskite (Ba2ZnUO6). Experimental data analysis by simulating the absorption edge allows to compare the coordination polyhedrons, identify the electronic transitions and calculate the density of states associated with the absorption spectra. Moreover, a coupling between simulations of the experimental spectra and quantum chemical calculations is performed, in order to improve the model describing the final states and better understand the bonding properties of the cation with the ligand.

Currently, there are a variety of techniques to deposit metal thin films ranging from high vacuum techniques such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), through to solution methods like sol-gel. While the vacuum techniques can be limited by size and cost, sol-gel can be limited be the availability of appropriate precursors. All of these techniques have the further limitation that they cannot be used to coat porous materials conformally.

Polymer assisted deposition (PAD) addresses some of the limitations of sol-gel and costs of high vacuum techniques. PAD utilizes an aqueous polymer to bind a metal or metal complex that serves both to encapsulate the metal to prevent chemical reaction and maintain an even distribution of the metal in solution. Another advantage that PAD has is that the same solution can be used as precursors for the growth of metal oxide or reduced metal films. Herein, we report on the utility of PAD in preparing metal oxide films used to conformally coat porous material and reduced metal films.

Raman spectroscopy can be performed with micrometer resolution and can thus be used to determine the dependence of oxide thickness on the substrate’s grain structure or local impurity inclusions. The Raman signal amplitude emitted from an epitaxial uranium oxide layer as a function of oxide thickness has been modeled for light of 632.8 nm wavelength incident on the oxide and reflected from the uranium substrate using the optical properties determined by spectrophotometry. The model shows that the Raman signal increases with oxide thickness and saturates at about 150 nm thickness. The model was compared with the measured Raman signal amplitude of an epitaxial uranium oxide layer growing in air with a known time dependence of oxide growth.

The purpose of this paper is to provide an introduction for non-experts to first-principles electronic structure methods that are widely used in the field of condensed-matter physics, including applications to actinide materials. The methods I describe are based on density functional theory (DFT) within the local density approximation (LDA) and the generalized gradient approximation (GGA). In addition to explaining the meaning of this terminology I also describe the underlying theory itself in some detail in order to enable a better understanding of the relative strengths and weaknesses of the methods. I briefly mention some particular numerical implementations of DFT, including the linear muffin-tin orbital (LMTO), linear augmented plane wave (LAPW), and pseudopotential methods, as well as general methodologies that go beyond DFT and specifically address some of the weaknesses of the theory. The last third of the paper is devoted to a few selected applications that illustrate the ideas discussed in the first two-thirds. In particular, I conclude by addressing the current controversy regarding magnetic DFT calculations for actinide materials. Throughout this paper particular emphasis is placed on providing the appropriate background to enable the non-expert to gain a better appreciation of the application of first-principles electronic structure methods to the study of actinide and other materials.

The investigation of the actinides is of great interest because of their unique electronic structure. At the pivotal point of the behavior of the electronic structure of the actinide series is plutonium. Pu has the most complex phase diagram of all metals, both with regard to the intricacy of the crystal structures and the number of different phases. While there are a number of ongoing experimental efforts directed at determining the occupied electronic structure of Pu, there is essentially no experimental data on the unoccupied electronic structure of Pu. We aim to determine the conduction band (unoccupied) electronic structure of Pu and other actinides in a phase specific fashion and emphasizing bulk contributions by using Nano-focussed Bremstrahlung Isochromat Spectroscopy (nBIS). BIS is the high-energy variant of inverse photoelectron spectroscopy (IPES: electron in, photon out), which is essentially the time reversal of photoelectron spectroscopy (photon in, electron out). IPES can be used to follow the dispersion of electronic states in ordered samples. Owing to its low energies, IPES is usually very surface sensitive. However, by working at higher energies, we will sample preferentially for bulk properties, downgrading the impact of surface effects. Thus, from BIS, we would have a direct measure of the conduction band or unoccupied electronic structure of the bulk Pu. By using a nano-focused electron source associated with a SEM, we hope to gather phase specific information from crystallites within polycrystalline Pu samples. We will discuss the experimental arrangement required to carry out such an experiment and our progress in building such a system.

The effect of the relativistic spin-orbit (SO)interaction on the bonding in the early actinides has been investigated by means of electronic-structure calculations. Specifically, the equation of state (EOS) for the face-centered cubic (fcc) model systems of these metals has been calculated from the first-principles density-functional (DFT) theory. Traditionally, the SO interaction in electronic-structure methods is implemented as a perturbation to the Hamiltonian that is solved for basis functions that explicitly do not depend on SO coupling. Here this approximation is shown to compare well with the fully relativistic Dirac treatment. It is further shown that SO coupling has a gradually increasing effect on the EOS as one proceeds through the actinides and the effect is diminished as density increases.

The production of H2 from alpha-particle radiolysis of water adsorbed onto plutonium dioxide powders has been studied. Plutonium dioxide powders with specific surface areas of 1.0 and 21 m2/g were used. The specific surface area strongly affects the amount of water adsorbed. At water coverage between 1 and 2 monolayers the H2 yield per unit of energy deposited into the water is found to be between 0.05 and 0.13 molecules of H2 per 100 eV adsorbed dose (5 to 12 nmols/s W). The H2 yield increases to between 0.29 and 0.58 molecules per 100 eV adsorbed dose (28 to 56 nmol/s W) when the number of adsorbed monolayers of water is between 10 and 20. The latter H2 yield is similar to that of liquid water of 0.45 molecules per 100 eV adsorbed dose