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Data on the Hafnium Dioxide Content and the Ratio of Hafnium to Zirconium in Minerals and Rocks

Description: Abstract: "All published data on the hafnium content and hafnium/zirconium ratio in minerals and rocks have been compiled." Information regarding hafnium and zirconium content and the ratio Hf/Zr in the earth's crust and in rocks as well as of minerals is included.
Date: March 1954
Creator: Fleischer, Michael
Partner: UNT Libraries Government Documents Department

Extraction of Zirconium and Hafnium with Various Fluorinated [beta]-Diketones

Description: Abstract: "The distribution ratios and equilibrium constants for the extraction of zirconium and hafnium from 4 M perchloric acid with various combinations of fluorinated [beta]-diketones and organic solvents have been determined. The separation factors K'Zr/K'HF, found for this acidity were: Z-thenoyltrifluoroacetone in benzene, 25; Z-thenoyltrifluoroacetone in o-dichlorobenzene, 16; benzoyltrifluoroacetone in benzene, 18; isovaleroyltrifluoroacetone in benzene, 13; isovaleroyltrifluoroacetone in n-hexane, 13."
Date: April 5, 1954
Creator: Huffman, E. H.; Iddings, G. M; Osborne, R. N. & Shalimoff, G. V.
Partner: UNT Libraries Government Documents Department

Zirconium Metal Fines Recovery: Interim Technical Report for May 15, 1950 to December 15, 1950

Description: This report covers the laboratory and pilot plant investigation of the reclamation of the low hafnium zirconium fines resulting from the manufacture of zirconium sponge and zirconium crystal bar. The process investigated involved recovery of the zirconium as zirconium tetrachloride, by drying the fines in an atmosphere of nitrogen and subsequent chlorination of the fines with anhydrous hydrogen chloride at temperatures above the sublimation point of the product.
Date: January 24, 1951
Creator: Ogburn, S. C., Jr. & Reader, L. J.
Partner: UNT Libraries Government Documents Department

The Spectrochemical Analysis of Hafnium and Zirconium

Description: Abstract: "The analysis of hafnium and zirconium by the copper spark technique is presented for solutions of HCl, HF, and HClO4 acids. The special techniques of electrode protection and vacuum drying of perchloric acid samples are outlined. Also given are the working curves and deviations of both elements."
Date: March 16, 1949
Creator: Conway, John G. & Moore, Milton F.
Partner: UNT Libraries Government Documents Department

Extraction of short-lived zirconium and hafnium isotopes usingcrown ethers: A model system for the study of rutherfordium

Description: The extraction of zirconium and hafnium from hydrochloric acid media was studied using the crown ethers dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DC18C6) and dicyclohexano-24-crown-8 (DC24C8) as extractants. The goal was to find an extraction system that exhibits a high selectivity between the members of group 4 of the periodic table and is suitable for the study of rutherfordium. It was found that Zr and Hf are both extracted using DB18C6, DC18C6 and DC24C8. The extraction yield increases with increasing acid concentration and increasing concentration of crown ether. The extracted species most likely consists of an ion-association complex formed between a Zr or Hf chloro complex and a hydronium crown ether complex. Conditions can be found for each extractant that provide for the separation of Zr from Hf. This selective separation between Zr and Hf makes the extraction with crown ethers from HCl well suited to study the extraction behavior of Rf and compare it to the behavior of Zr and Hf. These extraction systems can be used to determine whether the extraction behavior of Rf is similar to Zr, similar to Hf or follows the trend established by the lighter homologs. The extraction kinetics are fast enough for the study of the 78-s isotope {sup 261}Rf.
Date: July 6, 2005
Creator: Sudowe, Ralf; Calvert, Michael G.; Dullmann, Christoph E.; Farina, Lindsy M.; Folden III, Charles M.; Gregorich, Kenneth E. et al.
Partner: UNT Libraries Government Documents Department

K-isomers in Hf nuclei at and beyond the neutron-rich edge of {beta}-stability.

Description: New high-K isomers are populated in {sup 180,181,182}Hf nuclei via inelastic excitation and transfer reactions, using pulsed {sup 238}U beams on Hf targets. The new data explore K-hindrances for different multipolarities and the role of residual spin-spin interactions for multi-quasiparticle (qp) configurations at the neutron-rich edge of the {beta}-stability line. The mapping of 4-qp K-isomers in the A {approx} 180 region is extended into neutron-rich territory.
Date: March 30, 1999
Creator: Chowdhury, P.; Alarcao, R. D.; Seabury, E. H.; Walker, P. M.; Wheldon, C.; I., Ahmad. et al.
Partner: UNT Libraries Government Documents Department

Recovery of Zirconium Tetrachloride Powder

Description: Report discussing methods for recovering hafnium-free zirconium from irradiated fuel elements. Two methods are discussed: the fluoride method and the Zircex method. Experimental procedures to evaluate these methods and their results are presented.
Date: April 6, 1956
Creator: Lee, L. A. & Welt, M. A.
Partner: UNT Libraries Government Documents Department

Materials properties of hafnium and zirconium silicates: Metal interdiffusion and dopant penetration studies.

Description: Hafnium and Zirconium based gate dielectrics are considered potential candidates to replace SiO2 or SiON as the gate dielectric in CMOS processing. Furthermore, the addition of nitrogen into this pseudo-binary alloy has been shown to improve their thermal stability, electrical properties, and reduce dopant penetration. Because CMOS processing requires high temperature anneals (up to 1050 °C), it is important to understand the diffusion properties of any metal associated with the gate dielectric in silicon at these temperatures. In addition, dopant penetration from the doped polysilicon gate into the Si channel at these temperatures must also be studied. Impurity outdiffusion (Hf, Zr) from the dielectric, or dopant (B, As, P) penetration through the dielectric into the channel region would likely result in deleterious effects upon the carrier mobility. In this dissertation extensive thermal stability studies of alternate gate dielectric candidates ZrSixOy and HfSixOy are presented. Dopant penetration studies from doped-polysilicon through HfSixOy and HfSixOyNz are also presented. Rutherford backscattering spectroscopy (RBS), heavy ion RBS (HI-RBS), x-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), and time of flight and dynamic secondary ion mass spectroscopy (ToF-SIMS, D-SIMS) methods were used to characterize these materials. The dopant diffusivity is calculated by modeling of the dopant profiles in the Si substrate. In this disseration is reported that Hf silicate films are more stable than Zr silicate films, from the metal interdiffusion point of view. On the other hand, dopant (B, As, and P) penetration is observed for HfSixOy films. However, the addition of nitrogen to the Hf - Si - O systems improves the dopant penetration properties of the resulting HfSixOyNz films.
Date: August 2002
Creator: Quevedo-Lopez, Manuel Angel
Partner: UNT Libraries

Separation of Zirconium & Hafnium : Proposal for Construction & Operation of Zirconium Production Plant

Description: Abstract: A re-evaluation of the cost of producing essentially hafnium free zirconium as zirconium oxide at a rate of 150,000-200,000 pounds zirconium per year by solvent extraction of the metal thiocyanates in a permanent plant has been made. Using part of the present temporary facilities, the cost, with five year amortization of the plant, will be $3.15 per pound zirconium. A by-product of the mixed oxides of hafnium and zirconium, having at least fifty percent hafnium and perhaps as high as ninety percent hafnium, can be made available with little additional cost.
Date: November 17, 1955
Creator: Googin, J. M. & Strasser, G. A.
Partner: UNT Libraries Government Documents Department

Determination of Hafnium and Rare Earths in Aluminum Alloys

Description: Procedures are described for both a titrimetric and a gravimetric determination of hafnium in aluminum -hafnium alloys. The gravimetric procedure is used if the hafnium is to be recovered; otherwise, the titrimetric procedure is preferred. The sample is dissolved in aqua regia. Any undissolved hafnium is taken into solution via pyrosulfate fusion. The hafnium is separated from the aluminum and contaminants in the aluminum by precipitation as the mandelate. In the gravimetric procedure the hafnium mandelate is heated to the oxide, then weighed. In the titrimetric procedure the mandelate is destroyed with nitric, sulfuric, and perchloric acids. The hafuium then is determined by adding a measured excess of EDTA and back titrating the excess EDTA with a standard bismuth solution to a xylenol orange end point. (auth)
Date: January 1, 1959
Creator: Sikes, J. H.; Wade, M. A. & Yamamura, S. S.
Partner: UNT Libraries Government Documents Department

Ductile nickel-silicon alloy

Description: An improvement over prior compositions wherein the ductility of Ni-Si alloys are improved with minor alloying additions of hafnium or zirconium.
Date: August 6, 1990
Creator: Oliver, W.C.
Partner: UNT Libraries Government Documents Department

Hafnium Resonance Parameter Analysis Using Neutron Capture and Transmission Experiments

Description: The focus of this work is to determine the resonance parameters for stable hafnium isotopes in the 0.005 - 200 eV region, with special emphasis on the overlapping {sup 176}Hf and {sup 178}Hf resonances near 8 eV. Accurate hafnium cross sections and resonance parameters are needed in order to quantify the effects of hafnium found in zirconium, a metal commonly used in reactors. The accuracy of the cross sections and the corresponding resonance parameters used in current nuclear analysis tools are rapidly becoming the limiting factor in reducing the overall uncertainty on reactor physics calculations. Experiments measuring neutron capture and transmission are routinely performed at the Rensselaer Polytechnic Institute (RPI) LINAC using the time-of flight technique. {sup 6}Li glass scintillation detectors were used for transmission experiments at flight path lengths of 15 and 25 m, respectively. Capture experiments were performed using a sixteen section NaI multiplicity detector at a flight path length of 25 m. These experiments utilized several thicknesses of metallic and isotope-enriched liquid Hf samples. The liquid Hf samples were designed to provide information on the {sup 176}Hf and {sup 178}Hf contributions to the 8 eV doublet without saturation. Data analyses were performed using the R-matrix Bayesian code SAMMY. A combined capture and transmission data analysis yielded resonance parameters for all hafnium isotopes from 0.005 - 200 eV. Additionally, resonance integrals were calculated, along with errors for each hafnium isotope, using the NJOY and INTER codes. The isotopic resonance integrals calculated were significantly different than previous values. The {sup 176}Hf resonance integral, based on this work, is approximately 73% higher than the ENDF/B-VI value. This is due primarily to the changes to resonance parameters in the 8 eV resonance, the neutron width presented in this work is more than twice that of the previous value. The calculated elemental ...
Date: February 6, 2007
Creator: Trbovich, M J; Barry, D P; Slovacek, R E; Danon, Y; Block, R C; Francis, N C et al.
Partner: UNT Libraries Government Documents Department