13536-84-0Relevant academic research and scientific papers
Uranium-oxygen bond lengths in uranyl salts: Uranyl fluoride and uranyl carbonate
Hoekstra, Henry R.
, p. 492 - 495 (1963)
Infrared absorption curves for carefully purified samples of UO2F2 and UO2CO3 have been obtained. Using the new frequencies and Badger's rule, the uranyl bond lengths are calculated as 1.71 ?. in UO2F2 and 1.72 ?. in UO2CO3, in very good agreement with the Zachariasen bond length-bond strength relationship. Evidence is given to show that the U-O bond length in different uranyl salts shows relatively little variation (1.71-1.76 ?.) and that the bond order in the simple anhydrous salts may approach three.
Synthesis, characterization, and structure of uranium oxide tetrafluoride
Paine,Ryan,Asprey
, p. 1113 - 1117 (1975)
The synthesis of uranium oxide tetrafluoride from the combination of uranium hexafluoride and quartz wool (SiO2) in anhydrous hydrogen fluoride solution is reported. The slow reaction 4HF + SiO2 → SiF4 + 2H2O provides a stoichiometric, one-step, controlled, partial hydrolysis of UF6. The characterization of UOF4 including electronic and vibrational spectra of the solid is presented. The crystal structure as determined from three-dimensional single-crystal X-ray data collected by counter methods is described. A full-matrix least-squares refinement using 300 observed reflections resulted in a final R = 4.2%. The structure refines in the trigonal space group R3m. The hexagonal cell constants are a = 13.22 (1) ? and c = 5.72 (1) ? with V = 865.7 cm3, dc = 5.70 g/cm3, and Z = 9. The idealized coordination sphere of UOF4 consists of a pentagonal bipyramid of light atoms surrounding the central uranium. An oxygen atom and fluorine atom occupy indistinguishable axial positions with the U-O and U-F distances in the range 1.77-1.79 (3) ?. The equatorial belt contains one unique unbridged fluorine (U-Feq = 1.98 (3) ?) and four bridged fluorines (U-Fbr = 2.25-2.29 (3) ?). The observed chemistry and structure are compared and discussed in relation to transition metal oxide tetrafluorides and previously reported uranium oxide fluorides.
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.
Synthesis and structure of a new modification of monoaquadifluorouranyl hydrate
Mikhailov,Gorbunova,Stolyarov,Moiseev
, p. 1821 - 1826 (2008/10/08)
A new modification of monoaquadifluorouranyl hydrate was synthesized. Its composition and structure were determined by X-ray diffraction. The crystal is monoclinic: a = 13.843(3) ?, b = 9.801(3) ?, c = 24.970(5) ?, β= 104.47(3)°; space group C2/c. A unit cell (V = 3280(1) ?3) contains four formula units [(UO2) 7F14(H2O)7]·4H2O. The structure includes four nonequivalent uranium atoms: one of them (U(4)) occupies a special position (0, y, 1/4); the oxygen atom (O(11)) of one of the four coordinated water molecules is in the same position. Therefore, the compound can be formulated as [(UO2)3.5F 7(H2O)3.5]·2H2O; consequently, in space group C2/c, Z = 8. This composition corresponds to the stoichiometry of the low-water-content monodifluorouranyl hydrate [UO 2F2H2O]·0.57H2O. A uranyl compound with such a composition has not heretofore been described.
Preparation and Characterization of U2O2F7
Asada, Kameo,Ema, Keiko,Iwai, Takashi
, p. 3189 - 3194 (2007/10/02)
Reaction of UO2F2 with UF5 at 400 deg C under UF6-pressure of 3 atm followed by evaporation of excess UF5 has yielded a greenish white residue.Its X-ray diffraction pattern and infrared spectrum are sufficiently unique to establish that this material is a true compound.Its chemical formula has been shown to be U2O2F7, on the grounds of chemical analysis and thermal decomposition.The oxygen content was determined directly by means of 18O isotopic dilution method based on the combustion of the samples with BrF5.
