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The Vapor Phase Hydrolysis of the Trichlorides of Lanthanum, Praseodymium, Samarium, and Americium

Description: The following report studies the reactions of vapor phase hydrolysis of the trichlorides of lanthanum, praseodymium, samarium, and americium with gas mixtures of HCl and H2O passing over the solid materials mounted on a cantilever-type quartz fiber microbalance. This report calculates the values of the heats and entropies of the reactions, as well as the heat formation of LaCl3, 1254.9 kcal mol-(-1) that was obtained by determining the heat of the solution of La metal in 1.5M HCl.
Date: 1943
Creator: Broido, Abraham
Partner: UNT Libraries Government Documents Department

Stoichiometry, spin fluctuations, and superconductivity in LaNiPO

Description: Superconductivity in LaNiPO is disrupted by small ({approx}5%) amounts of non-stoichiometry on the lanthanum site, even though the electronic contribution to the heat capacity increases with increasing non-stoichiometry. All samples also exhibit specific heat anomalies consistent with the presence of ferromagnetic spin fluctuations (T{sub sf}{approx} 14K). Comparison of layered nickel phosphide and nickel borocarbide superconductors reveals different structure-property correlations in the two families.
Date: January 1, 2009
Creator: Klimczuk, Tomasz; Mcqueen, Tyrel M; Williams, Anthony J; Huang, Qiang & Cava, Robert J
Partner: UNT Libraries Government Documents Department

Determination of Stability Constants of Hydrogen and Aluminum Fluorides with a Fluoride-Selective Electrode

Description: The ability to directly determine free fluoride ion concentration (or mean activity) simplifies gathering and interpretation of experimental data for studies of metal complexes. In this work, the new lanthanum fluoride electrode was used to measure free fluoride ion in an investigation of the hydrogen-fluoride and aluminum-fluoride systems in NH4NO3.
Date: January 6, 2003
Creator: Baumann, E.W.
Partner: UNT Libraries Government Documents Department

Effect of electrode material and design on sensitivity and selectivity for high temperature impedancemetric NOx sensors

Description: Solid-state electrochemical sensors using two different sensing electrode compositions, gold and strontium-doped lanthanum manganite (LSM), were evaluated for gas phase sensing of NO{sub x} (NO and NO{sub 2}) using an impedance-metric technique. An asymmetric cell design utilizing porous YSZ electrolyte exposed both electrodes to the test gas (i.e., no reference gas). Sensitivity to less than 5 ppm NO and response/recovery times (10-90%) less than 10 s were demonstrated. Using an LSM sensing electrode, virtual identical sensitivity towards NO and NO{sub 2} was obtained, indicating that the equilibrium gas concentration was measured by the sensing electrode. In contrast, for cells employing a gold sensing electrode the NO{sub x} sensitivity varied depending on the cell design: increasing the amount of porous YSZ electrolyte on the sensor surface produced higher NO{sub 2} sensitivity compared to NO. In order to achieve comparable sensitivity for both NO and NO{sub 2}, the cell with the LSM sensing electrode required operation at a lower temperature (575 C) than the cell with the gold sensing electrode (650 C). The role of surface reactions are proposed to explain the differences in NO and NO{sub 2} selectivity using the two different electrode materials.
Date: September 23, 2009
Creator: Woo, L Y; Glass, R S; Novak, R F & Visser, J H
Partner: UNT Libraries Government Documents Department

The Mechanism of Carrying Pu(III) on Lanthanum Fluoride

Description: From introduction: "Analytical procedures for the determination of plutonium samples from the extraction and concentration plants utilize the carrying of the hydroxylamine-reduced trivulent plutonium by coprecipitation on lanthanum fluoride. Most other plutonium procedures also take advantage of the efficient carrying on lanthanum fluoride."
Date: April 15, 1952
Creator: Ralphs, Delbert Lloyd
Partner: UNT Libraries Government Documents Department

Report for General Research September 18 to December 11, 1950 (Actinium Volume)

Description: The purpose of the research work presented in this volume is to develop a process for the separation and purification of actinium-227 produced by neutron bombardment of radium-226 and to develop methods by which uniform films of actinium metal may be deposited on metallic surfaces. The design work on the cave structure and mechanical equipment used in the actinium separation is proceeding on schedule. As the mechanical design phase is nearing completion the emphasis is being directed toward processing equipment. The process as well as the mechanical equipment has been adapted from the research work of F. T. Hagemann and the Remote Control Group at Argonne National Laboratory. Consequently, one of the first objectives is to become familiary with the chemistry of the process and the operation of the mechanical equipment. Cold runs have been made on the T.T.A. benzene extraction using lanthanum and barium in place of actinium and radium. No difficulty with the operation was observed. The formation of precipitates was one of the difficulties encountered with the process as the precipitates carry radium. It has been found that metals such as nickel cause these precipitates to form and should, therefore, be avoided in the construction of equipment. it was also found that a T.T.A. solution exposed to 0.5 curie of polonium over a period of days develops a precipitate. Some new mechanical features hav eshown promise. The use of copper-coated glassware which will hold together even though the glass is cracked has made it possible to replace custom-built heaters with standard heating mantles. A new graphite, silicone grease mixture appears to hold up in stopcocks handling benzene and, as a result, may eliminate the necessary of entering the cave for regreasing. Tests on the preparation of dense concrete have given results which meet the shielding requirements for ...
Date: January 15, 1951
Creator: Haring, M.M.
Partner: UNT Libraries Government Documents Department

Adsorption of lanthanum to goethite in the presence of gluconate

Description: Adsorption of Lanthanum to Goethite in the Presence of Gluconic Acid L. C. HULL,1 S. E. PEPPER2 AND S. B. CLARK2 1Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (hulllc@inel.gov) 2Washington State University, Pullman, WA (spepper@wsu.edu), (s_clark@wsu.edu) Lanthanide and trivalent-actinide elements in radioactive waste can pose risks to humans and ecological systems for many years. Organic complexing agents, from natural organic matter or the degradation of waste package components, can alter the mobility of these elements. We studied the effect of gluconic acid, as an analogue for cellulose degradation products, on the adsorption of lanthanum, representing lanthanide and trivalent-actinide elments, to goethite, representing natural iron minearals and degradation products of waste packages. Batch pH adsorption edge experiments were conducted with lanthanum alone, and with lanthanum and gluconate at a 1:1 mole ratio. Lanthanum concentrations studied were 0.1, 1, and 10 mM, covering a range from 10% to 1000% of the calculated available adsorption sites on goethite. In the absence of gluconate, lanthanum was primarily present in solution as free lanthanum ion. With gluconate present, free lanthanum concentration in solution decreased with increasing pH as step-wise deprotonation of the gluconate molecule increased the fraction lanthanum complexed with gluconate. Adsorption to the goethite surface was represented with the diffuse double-layer model. The number of adsorption sites and the intrinsic binding constants for the surface complexes were estimated from the pH adsorption edge data using the computer code FITEQL 4.0. Two surface reactions were used to fit the adsorption data in the absence of gluconate. A strong binding site with no proton release and a much higher concentration of weak binding sites with release of two protons per lanthanum adsorbed. The adsorption of lanthanum was not measurably affected by the presence of gluconate below pH 7. At pH values above 7, however, ...
Date: May 1, 2005
Creator: Hull, Laurence C.; Pepper, Sarah & Clark, Sue
Partner: UNT Libraries Government Documents Department

Interaction of Pu(IV,VI) hydroxides/oxides with metal hydroxides/oxides in alkaline media

Description: The primary goal of this investigation was to obtain data on the possibility, extent, and characteristics of interaction of Pu(IV) and (VI) with hydroxides and oxides of d-elements and other metals [Al(III), LA(III), and U(VI)] in alkaline media. Such information is important in fundamental understanding of plutonium disposition and behavior in Hanford Site radioactive tank waste sludge. These results supply essential data for determining criticality safety and in understanding transuranic waste behavior in storage, retrieval, and treatment of Hanford Site tank waste.
Date: August 1, 1998
Creator: Fedoseev, A.M.; Krot, N.N.; Budantseva, N.A.; Bessonov, A.A.; Nikonov, M.V.; Grigoriev, M.S. et al.
Partner: UNT Libraries Government Documents Department

The phase diagrams and doped-hole segregation in La{sub 2}CuO{sub 4+{delta}} and La{sub 2-x}Sr{sub x}CuO{sub 4+{delta}} (x {le} 0.15, {delta} {le} 0.12)

Description: The magnetic and structural phase diagrams of the La{sub 2}CuO{sub 4+{delta}} system and the La{sub 2-x}Sr{sub x}CuO{sub 4+{delta}} are reviewed, with emphasis on recent results obtained from magnetic and structural neutron diffraction, thermogravimetric analysis, iodometric titration, magnetic susceptibility {chi}(T), and {sup 129}La nuclear quadrupole resonance (NQR) measurements.
Date: October 31, 1993
Creator: Johnston, D.C.; Borsa, F. & Canfield, P.C.
Partner: UNT Libraries Government Documents Department

RAPID SEPARATION OF ACTINIDES AND RADIOSTRONTIUM IN VEGETATION SAMPLES

Description: A new rapid method for the determination of actinides and radiostrontium in vegetation samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations or for routine analysis. The actinides in vegetation method utilizes a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a streamlined column separation process with stacked TEVA, TRU and DGA Resin cartridges. Lanthanum was separated rapidly and effectively from Am and Cm on DGA Resin. Alpha emitters are prepared using rare earth microprecipitation for counting by alpha spectrometry. The purified {sup 90}Sr fractions are mounted directly on planchets and counted by gas flow proportional counting. The method showed high chemical recoveries and effective removal of interferences. The actinide and {sup 90}Sr in vegetation sample analysis can be performed in less than 8 h with excellent quality for emergency samples. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory actinide particles or vegetation residue after furnace heating is effectively digested.
Date: June 1, 2010
Creator: Maxwell, S.
Partner: UNT Libraries Government Documents Department

Directly heated LaB/sub 6/ cathodes for ion source operation

Description: Some physical properties of lanthanum hexaboride ''filaments,'' when operated as cathodes in a gas discharge, are presented. These directly heated hairpin shaped filaments have been tested in different types of ion sources and are shown to be capable of long pulse or cw discharge operations. The characteristics of a shaped lanthanum hexaboride filament for the purpose of further extension of lifetime is described. The design and operation of a magnetic-field-free, directly-heated, coaxial LaB/sub 6/ cathode is also discussed.
Date: March 1, 1986
Creator: Leung, K.N.
Partner: UNT Libraries Government Documents Department

QUARTERLY REPORT, JANUARY 1, 1960-MARCH 31, 1960

Description: Three methods for the determination of radium were evaluated. In two methods, the radium is finally precipitated with barium sulfate as carrier and alpha-counted. In the other method, the radium is recovered in a carrierfree condition for alpha counting. A method for determining radium by removing interfering elements with solvent extraction technniques and precipitating the radium with barium sulfate is described. A method which gives a rapid estimation of radium isotopic composition in samples, based on precipitation with barium sulfate, conversion to the carbonate, and alpha counting, is described. Flowsheets are contained on all five processes discussed. Two processes for the determination of thorium were evaluated. One method consists essentially of extraction of carrierfree thorium in TTA-benzene, stripped in nitric acid, and direct plating of the nitric acid solution for counting. The second method consists of thorium precipitation on lanthanum hydroxide, then on lanthanum fluoride, dissolution in nitric acid aluminum nitrate, thorium extraction into TTA solution, stripping into nitric acid, and counting. Flowsheets for the processes are given. The effects of pH, sulfate ion concentration, calcium and other contaminants, and temperature on the adsorption of radium from acid leach liquors by barite were studied. Coprecipitation studies of radium with barium sulfate from mill effluent streams were investigated. (For preceding period see WlN-115.) (C.J.G.)
Date: October 31, 1960
Creator: Herrington, A.C. comp. and ed.
Partner: UNT Libraries Government Documents Department