Molecular and Supramolecular Study of Uranium/Plutonium Liquid-Liquid Extraction with ,-Dialkylamides.

In the context of the separation of uranium and plutonium from spent fuel allowed by -dialkylamides, three regioisomers of -di(2-ethylhexyl) butyramide (DEHBA or ββ) and the diastereopure isomers of -(2-ethylhexyl)--(oct-3-yl)butyramide (EHOBA or αβ) were synthesized to assess their extraction performance and to study the mechanisms at the origin of the differences observed between the stereo- and regioisomers. The -dialkylamides showed differences in extraction, with a greater effect of regio- than stereoisomerism. A mechanistic study at both the molecular and supramolecular scales was initially applied to explain these effects.

Chronicles of plutonium peroxides: spectroscopic characterization of a new peroxo compound of Pu(IV).

Although hydrogen peroxide (HO) has been highly used in nuclear chemistry for more than 75 years, the preparation and literature description of tetravalent actinide peroxides remain surprisingly scarce. A new insight is given in this topic through the synthesis and thorough structural characterization of a new peroxo compound of Pu(IV).

Incorporation of U(IV) in monazite-cheralite ceramics under oxidizing and inert atmospheres.

This work is the first attempt to prepare NdCaUPO monazite-cheralite with 0 < ≤ 0.1 by a wet chemistry method. This method relies on the precipitation under hydrothermal conditions ( = 110 °C for four days) of the NdCaUPO·HO rhabdophane precursor, followed by its thermal conversion for 6 h at 1100 °C in air or Ar atmosphere.

Interaction Between the Transferrin Protein and Plutonium (and Thorium), What's New?

Transferrin (Tf) is a glycoprotein that transports iron from the serum to the various organs. Several studies have highlighted that Tf can interact with metals other than Fe(III), including actinides that are chemical and radiological toxics. We propose here to report on the behavior of Th(IV) and Pu(IV) in comparison with Fe(III) upon Tf complexation.

How hydrothermal synthesis improves the synthesis of (Zr,Ce)SiO solid solutions.

Although ZrSiO is the most well-known compound in the zircon-structured family (space group 4/), the experimental conditions for preparing pure and well-crystallized phases that are doped with a tetravalent element hydrothermal synthesis have never been clearly discussed in the literature. With the aim to answer this question, the experimental conditions of the preparation of ZrSiO and (Zr,Ce)SiO were investigated in order to synthesize well-crystallized and pure phases. A multiparametric study has been carried out using soft hydrothermal conditions with variables including reactant concentration, initial pH of the reactive medium, and duration of the hydrothermal treatment.

First observation of [Pu(OH)O] cluster during the hydrolytic formation of PuO nanoparticles using H/D kinetic isotope effect.

New insights are provided about the formation mechanism of PuO nanoparticles (NPs) by investigating an unprecedented kinetic isotope effect observed during their hydrolytic synthesis in HO or DO and attributed to OH/OD zero point energy difference. The signature of a Pu(IV) oxo-hydroxo hexanuclear cluster, appearing as an important intermediate during the formation of the 2 nm PuO NPs (synchrotron SAXS/XAS), is further revealed indicating that their formation is controlled by H-transfer reactions occurring during hydroxo to oxo-bridge conversions.

Size and structure of hexanuclear plutonium oxo-hydroxo clusters in aqueous solution from synchrotron analysis.

The size and shape of a water-soluble hexanuclear plutonium cluster were probed by combining synchrotron small-angle X-ray scattering (SAXS) and extended X-ray absorption fine structure (EXAFS). A specific setup coupling both techniques and dedicated to radioactive samples on the MARS beamline endstation at Synchrotron SOLEIL is described. The plutonium hexanuclear cores are well stabilized by the 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid ligands and this allows a good evaluation of the setup to probe the very small plutonium core.

Local-Disorder-Induced Low Thermal Conductivity in Degenerate Semiconductor CuSnS.

S-based semiconductors are attracting attention as environmentally friendly materials for energy-conversion applications because of their structural complexity and chemical flexibility. Here, we show that the delicate interplay between the chemical composition and cationic order/disorder allows one to stabilize a new sphalerite derivative phase of cubic symmetry in the Cu-Sn-S diagram: CuSnS. Interestingly, its crystal structure is characterized by a semiordered cationic distribution, with the Cu-Sn disorder being localized on one crystallographic site in a long-range-ordered matrix.

Micro-laser-induced breakdown spectroscopy technique: a powerful method for performing quantitative surface mapping on conductive and nonconductive samples.

Laser-induced breakdown spectroscopy (LIBS) has been applied mainly to bulk analysis of solids, liquids, and gases and less frequently for elemental microanalysis of solid surfaces. A micro-LIBS device devoted to analysis of the distribution of elements on surfaces is described. This device offers rapid access with a 3-microm spatial resolution to the microchemical structures of both conductive and nonconductive samples.

Analysis by laser-induced breakdown spectroscopy of complex solids, liquids, and powders with an echelle spectrometer.

One of the most promising approaches to laser-induced breakdown spectroscopy (LIBS) experiments involves the use of an echelle spectrometer coupled with an intensified CCD. Even if drawbacks remain with its use, the echelle spectrometer facilitates a multielemental analysis that is more rapid than can be obtained with the more-conventional Czerny-Turner spectrometer and, moreover, does not sacrifice reliability. Quantitative results obtained with such apparatus for solids, liquids, powders, and gases are described and when possible compared with results from Czerny-Turner spectrometers.