7783-80-4Relevant articles and documents
Germain, Patrick,Claudy, Pierre,Letoffe, Jean-Marie,Bastide, Jean-Pierre
, p. 1731 - 1738 (1988)
Yost, D. M.,Claussen, W. H.
, p. 885 - 885 (1933)
Separation of metallic residues from the dissolution of a high-burnup BWR fuel using nitrogen trifluoride
McNamara, Bruce K.,Buck, Edgar C.,Soderquist, Chuck Z.,Smith, Frances N.,Mausolf, Edward J.,Scheele, Randall D.
supporting information, p. 1 - 8 (2014/05/06)
Nitrogen trifluoride (NF3) was used to fluorinate the metallic residue from the dissolution of a high burnup, boiling water reactor fuel (～70 MWd/kgU). The washed residue included the noble-metal phase (containing ruthenium, rhodium, palladium, technetium, and molybdenum), smaller amounts of zirconium, selenium, tellurium, and silver, along with trace quantities of plutonium, uranium, cesium, cobalt, europium, and americium, likely as their oxides. Exposing the noble metal phase to 10% NF3 in argon, between 400 and 550 °C, removed molybdenum and technetium near 400 °C as their volatile fluorides, and ruthenium near 500 °C as its volatile fluoride. The events were thermally and temporally distinct and the conditions specified provide a recipe to separate these transition metals from each other and from the nonvolatile residue. Depletion of the volatile fluorides resulted in substantial exothermicity. Thermal excursion behavior was recorded with the thermal gravimetric instrument operated in a non-adiabatic, isothermal mode; conditions that typically minimize heat release. Physical characterization of the noble-metal phase and its thermal behavior are consistent with high kinetic velocity reactions encouraged by the nanoparticulate phase or perhaps catalytic influences of the mixed platinum metals with nearly pure phase structure. Post-fluorination, only two products were present in the residual nonvolatile fraction. These were identified as a nano-crystalline, metallic palladium cubic phase and a hexagonal rhodium trifluoride (RhF3) phase. The two phases were distinct as the sub-μm crystallites of metallic palladium were in contrast to the RhF3 phase, which grew from the parent, nano-crystalline noble-metal phase during fluorination, to acicular crystals exceeding 20-μm in length.
Heptacoordination: Pentagonal bipyramidal XeF7+ and TeF7- ions
Christe, Karl O.,Dixon, David A.,Sanders, Jeremy C. P.,Schrobilgen, Gary J.,Wilson, William W.
, p. 9461 - 9467 (2007/10/02)
The TeF7- anion was studied experimentally by vibrational and 19F and 125Te NMR spectroscopy. Ab initio calculations employing effective core potentials and density functional theory calculations at the self-consistent nonlocal level with the nonlocal exchange potential of Becke and the nonlocal correlation functional of Perdew were used for the analysis of the isoelectronic series TeF7-, IF7, XeF7+. It is shown that XeF7+ is a stable structure, that all three members of this series possess a pentagonal bipyramidal equilibrium geometry, and that from the two closest lying saddle point geometries only the monocapped trigonal prism, but not the monocapped octahedron, is a transition state for the intramolecular axial-equatorial ligand exchange. The results from a normal coordinate analysis reveal the existence of an unusual new effect which counteracts the ligand-ligand repulsion effect and is characterized by axial bond stretching encouraging equatorial bond stretching. While in TeF7- the ligand-ligand repulsion effect dominates, in XeF7+ the new effect becomes preponderant.
