1,849 Matching Results

Search Results

Advanced search parameters have been applied.

The Preparation and Some Properties of a Uranium Hexafluoride-Sodium Fluoride Complex

Description: Report discussing "preparation of some stable complexes of uranium hexafluoride with sodium, potassium, and thallium fluorides...Such compounds, reported as stable in air and of low vapor pressure, offered promise as convenient sources of unoxygenated hexa-valent uranium without the difficulties associated with the use of uranium hexafluoride itself."
Date: November 30, 1950
Creator: Horton, Charles A.; Harris, Warren W.; Barr, John T. & Posey, J. C.
Partner: UNT Libraries Government Documents Department

Comparison of F(2)-Based Gases for High-Rate Dry Etching of Si

Description: Four different F{sub 2}-based gases (SF{sub 6}, NF{sub 3}, PF{sub 5}, and BF{sub 3}) were examined for high rate Inductively Coupled Plasma etching of Si. Etch rates up to {approximately}8 {micro}m/min were achieved with pure SF{sub 6} discharges at high source power (1500W) and pressure (35mTorr). A direct comparison of the four feedstock gases under the same plasma conditions showed the Si etch rate to increase in the order BF{sub 3} < NF{sub 3} < PF{sub 5} < SF{sub 6}. This is in good correlation with the average bond energies of the gases, except for NF{sub 3}, which is the least strongly bound. Optical emission spectroscopy showed that the ICP source efficiently dissociated NF{sub 3}, but the etched Si surface morphologies were significantly worse with this gas than with the other 3 gases.
Date: March 31, 1999
Creator: Donahue, J.; Hahn, Y.B.; Hays, D.C.; Johnson, D.; Jung, K.B.; Lambers, E.S. et al.
Partner: UNT Libraries Government Documents Department

Ultracentrifugal Measurements on Uranyl Fluoride Solutions

Description: Abstract: "Activity coefficient ratios for UO2F2 were measured at 30 C by ultracentrifugation to equilibrium. The method was checked with CdI2. The results for UO2F2 confirm the hypothesis of a monomer-diner equilibrium which was used previously to interpret the freezing point depressions of UO2F2 solutions. The dimerization constant at 30 C was found to be somewhat greater then at the freezing point. The proportionality constants for the dependence of the logarithm of the activity coefficients on molality were found to be essentially temperature independent. The heat and entropy of dimerization were estimated. Experiments in the presence of an indifferent electrolyte (NaClO4) support the assumption that dissociation into ions is slight. In potassium fluoride solutions, uranyl fluoride dimerizes more extensively than in water solutions."
Date: 1952
Creator: Johnson, James S. & Kraus, Kurt A.
Partner: UNT Libraries Government Documents Department

Identification of Reaction Products Formed During Magnesium Reduction of Uranium Tetrafluoride: Report

Description: Abstract: "This report describes the results of X-ray diffraction examination of reaction products from a series of experiments performed by Mallinckrodt Chemical Works as an acid in understanding the process of bomb reduction of UF4. UF4 is initially reduced to UF3 by magnesium at 560 C., and subsequently to metal at 600 C. MgF2 from the initial reaction forms a coating on the magnesium which retards the final spontaneous reaction."
Date: May 15, 1953
Creator: Schwartz, C. M. & Vaughan, D. A.
Partner: UNT Libraries Government Documents Department

The Preparation and Properties of Uranium Trifluoride

Description: From abstract: "The means of preparing uranium trifluoride are discussed. The most practical method is the reduction of uranium tetrafluoride with uranium although reduction with hydrogen or atomic hydrogen may also be feasible...A literature survey and discussion of other means of preparation are given."
Date: 1949
Creator: Warf, James C.
Partner: UNT Libraries Government Documents Department

Density and Refractive Index of Uranyl Fluoride Solutions

Description: "In the course of an ultracentrifugal investigation of uranyl fluoride solutions, their densities and refractive indices were measured as a function of concentration. The measurements were carried out near 25 and 30 C and if necessary extrapolated to 25.0 and 30.0 C from the observed temperature coefficients. Most density data were obtained pycnometrically (25 cc samples) and a few gradient tubes. The refractive index measurements were carried out with a Bausch and Lomb dipping refractometer (calibrated with "known" solutions) using sodium-D light. The materials used and the analytical procedures were described earlier. Although the accuracy of the density measurements was approximately one part in 10,000, the accuracy of the determinations at high UO2F2 concentration is considerably less, in view of the uncertainty in the uranium analyses."
Date: 1953
Creator: Johnson, James S. & Kraus, Kurt A.
Partner: UNT Libraries Government Documents Department

Effect of Fluoride on the Gravimetric Determination of Zirconium in Zirconium Fluoride

Description: Abstract: "The results of this investigation that it is necessary to remove fluoride prior to precipitation zirconium with mandelic acid or phenyl arsonic acid. Fluoride, however, has little effect on the cupferron method of precipitation. The discovery that zirconium fluoride is soluble in a mixture of aqua regia and sulfuric acid made it possible to dissolve the material without the addition of fluoride from hydrofluoric acid."
Date: June 3, 1952
Creator: McCutchen, R. L. & Susano, C. D.
Partner: UNT Libraries Government Documents Department

Dissolution of Uranium Tetrafluoride

Description: "Five new dissolution processes for uranium tetrafluoride are discussed-the NH4OH-H2O2 method, the H2SC4 - (NH4)2S2O8 method, the AlCl3 method, the NaAlcl method, and the Al (NO3)3.9E2O method. It is concluded that NaAlCl4 and Al(NO3)3.9H2O are preferable to the other agents, especially with regard to rate of dissolution and ease of manipulation."
Date: 1949
Creator: Calkins, V. P. & Susano, C. D.
Partner: UNT Libraries Government Documents Department

Freezing Point Diagram and Liquid-Liquid Solubilities of the System Uranium Hexafluoride-Hydrogen Fluoride

Description: Abstract: "The complete freezing point diagram for the system uranium hexafluoride-hydrogen fluoride has been determined. In addition, liquid-liquid solubilities of these compounds have been measured up to the consolute temperature of 101 C. A miscibility gap starts at 61.2 C. over the compositions range 10 to 80 mole per cent uranium hexafluoride. The lowest melting point of this binary system under its own pressure, i.e. the eutectic, is -85 C."
Date: December 28, 1952
Creator: Rutledge, Gene P.; Jarry, Roger L. & Davis, W.
Partner: UNT Libraries Government Documents Department

A Mill for the Quantitative Grinding of TF₄

Description: Abstract: "A monel metal rod mill has been designed, built, and tested for grinding five hundred gram batches of anhydrous tuballoy tetrafluoride to a fineness such that one hundred per cent will pass an eighty mesh screen; the grinding being accomplished without loss of material, and with the addition of less than two hundred parts per million of contaminating metals. The grinding time per batch is not more than fifty minutes."
Date: 1945
Creator: Webb, A. D.; Peed, W. F.; Pancoast, L. H. & Johnsson, Karl Otto
Partner: UNT Libraries Government Documents Department

Synthesis and evaluation of ultra-pure rare-earth-coped glass for laser refrigeration

Description: Significant progress has been made in synthesizing and characterizing ultra-pure, rare-earth doped ZIBLAN (ZrF{sub 4}-InF{sub 3}BaF{sub 2}-LaF{sub 3}-AlF{sub 3}-NaF) glass capable of laser refrigeration. The glass was produced from fluorides which were purified and subsequently treated with hydrofluoric gas at elevated temperatures to remove impurities before glass formation. Several Yb3 +-doped samples were studied with degrees of purity and composition with successive iterations producing an improved material. We have developed a non-invasive, spectroscopic technique, two band differential luminescence thermometry (TBDLT), to evaluate the intrinsic quality of the ytterbium doped ZIBLAN used for laser cooling experiments. TBDLT measures local temperature changes within an illuminated volume resulting solely from changes in the relative thermal population of the excited state levels. This TBDLT technique utilizes two commercially available band pass filters to select and integrate the 'difference regions' of interest in the luminescence spectra. The goal is to determine the minimum temperature to which the ytterbium sample can cool on the local scale, unphased by surface heating. This temperature where heating and cooling are exactly balanced is the zero crossing temperature (ZCT) and can be used as a measure for the presence of impurities and the overall quality of the laser cooling material. Overall, favorable results were obtained from 1 % Yb3+-doped glass, indicating our glasses are desirable for laser refrigeration.
Date: January 1, 2009
Creator: Patterson, Wendy M; Hehlen, Markus P; Epstein, Richard I & Sheik-bahae, Mansoor
Partner: UNT Libraries Government Documents Department

Spectrophotometry of Molten Fluoride Salts. Status Report

Description: Progress made in the field of spectrophotometry of molten fluoride salts is summarized. The high-temperature cell assembly designed and fabricated for use in this work is described, as well as the various types of sample containers used. Spectra of nickel fluoride, cobalt fluoride, chromic fluoride, and uranium tetrafluoride in LiF--NaF-KF (46.5-11.5--42 mole%) are presented. (auth)
Date: March 25, 1959
Creator: White, J. C.
Partner: UNT Libraries Government Documents Department