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Properties of Arc-Melted Chromium-Base Alloys

Description: From abstract: "Twelve binary chromium-base alloy systems were screened for hot workability, oxidation resistance, and hot strength using small ore-melted ingots...Experiments with the preparation of large chromium-base alloy ingots showed that cold-mold ore melting was not suitable for preparing ingots containing over about 1 w/o of alloy addition."
Date: July 14, 1958
Creator: Maykuth, Daniel J.; Roberts, John W., Jr. & Jaffee, Robert Isaac
Partner: UNT Libraries Government Documents Department

Solvent Extraction Concentration of Certain Rare Earths in Yttrium

Description: Abstract: A procedure is given for the concentration of gadolinium, dysprosium, and samarium in yttrium oxide by extraction of the thiocyanates with tributyl phosphate. Concentration of these elements up to 80-fold was obtained. Results are given on the effects of ammonium thiocynate and tributyl phosphate concentrations, as well as pH, temperature and sample size on the separation. Analyses of standard yttrium oxide samples after concentration of these rare earths are in good agreement with results obtained by direct spectrographic analyses.
Date: October 1957
Creator: Eberle, Allan R. & Lerner, M. W.
Partner: UNT Libraries Government Documents Department

Analysis of yttrium oxide exchange samples

Description: Report detailing the results of several yttrium oxide analyses. Four different institutions were given 50 grams of yttrium oxide to analyze following the Yttrium Analytical Conference on November 7th and 8th, 1956. This report details the results of those four different institutions.
Date: February 1958
Creator: Rodden, Clement J.
Partner: UNT Libraries Government Documents Department

The Neutron-Deficient Yttrium Isotopes Y$sup 82$, Y$sup 83$, and Y$sup 8$$Sup 4$

Description: Divergences in values of the half life of Y/sup 85/ have been resolved by discovery of a new sup 85/ isomeric state, and the half lives of Y/sup 84/ , Y/sup 83/, and Y/sup 82/ have been evaluated. Powdered arsenic metal targets were bombarded in the Berkeley heavy-ion linear accelerator with carbon ions. Determination by direct decay gives a half life of 39 plus or minus 1 min for Y/ sup 84/. Timed chemical separation values of 9 plus or minus 3 min and 8 plus or minus 2 min were obtained for Y/sup 84/ and Y/sup 83/, respectively. Gamma spectra of Y/sup 84/ and Sr/sup 83/ are shown. (D.C.W.)
Date: December 1, 1961
Creator: Maxia, V.; Kelly, W. H. & Horen, D. J.
Partner: UNT Libraries Government Documents Department

Yttrium Calcium Oxyborate for high average power frequency doubling and OPCPA

Description: Significant progress has been achieved recently in the growth of Yttrium Calcium Oxyborate (YCOB) crystals. Boules have been grown capable of producing large aperture nonlinear crystal plates suitable for high average power frequency conversion or optical parametric chirped pulse amplification (OPCPA). With a large aperture (5.5 cm x 8.5 cm) YCOB crystal we have demonstrated a record 227 W of 523.5nm light (22.7 J/pulse, 10 Hz, 14 ns). We have also demonstrated the applicability of YCOB for 1053 nm OPCPA.
Date: June 20, 2006
Creator: Liao, Z M; Jovanovic, I; Ebbers, C A; Bayramian, A; Schaffers, K; Caird, J et al.
Partner: UNT Libraries Government Documents Department

Oblique ion texturing of yttria-stabilized zirconia: The {l_brace}211{r_brace}<111> structure

Description: Amorphous (Zr,Y)O{sub x} films were synthesized by reactive magnetron sputtering and subsequently crystallized by oblique ion bombardment. Crystalline texture nucleated by the ion beam was replicated by solid-phase epitaxial growth throughout the formerly amorphous yttria-stabilized zirconia (YSZ) film. The resulting YSZ films have (211) orientation normal to the substrate with in-plane directions (111), parallel, and (110), transverse, to the azimuth of the ion beam. We hypothesize that the texture mechanism involves ion-induced film compression and shear. The results, taken together with prior work, show that oblique ion texturing of amorphous films is a general phenomenon that can be used to fabricate substrates with more than one type of crystallographic orientation.
Date: July 1, 2002
Creator: Berdahl, Paul; Reade, Ronald P.; Liu, Jinping; Russo, Richard E.; Fritzemeier, Les; Buczek, David et al.
Partner: UNT Libraries Government Documents Department

Crystal and magnetic structure of stoichiometric YFe{sub 2}O{sub 4}

Description: Crystal structure of stoichiometric YFe{sub 2}O{sub 4} powder was studied by high-resolution neutron diffraction at room temperature, 225 K and 80 K. Rietveld refinements of the diffraction patterns give reasonable fits with space group R{bar 3}m (hexagonal) for room temperature, and with P{bar 1} (triclinic) for 225 K. However, the 80 K pattern cannot be fitted at all with the same triclinic symmetry, indicating that the structure is much more complicated. The magnetic reflection has been separated from those complex nuclear peaks by the polarization analysis. The magnetic structure is also fairly complicated both at 225 K and at 80 K.
Date: August 1, 1994
Creator: Katano, S.; Funahashi, S.; Matsumoto, T.; Iida, J.; Tanaka, M. & Cable, J.W.
Partner: UNT Libraries Government Documents Department

Aqueous precipitation: Population balance modeling and control in multi-cation systems

Description: Efficient separation of metal species from aqueous streams by precipitation techniques requires a fundamental understanding of the processes that occur during precipitation. These processes include particle nucleation, particle growth by solute deposition, agglomerate formation, and agglomerate breakup. Population balance method has been used to develop a kinetic model that accounts for these competing kinetic processes. The usefulness of the model is illustrated through its application to precipitation of yttrium hydroxynitrate, YHN. Kinetic parameters calculated from the model equations and system-specific solution chemistry are used to describe several aspects of the effect of pH on YHN precipitation. Implications for simultaneous precipitation of more than one cation type are discussed with examples. Effects of solution chemistry, precipitator design, and solvent choice are considered.
Date: March 1996
Creator: Voigt, J. A.
Partner: UNT Libraries Government Documents Department

Vortex lattice structures in YNi{sub 2}B{sub 2}C

Description: The authors observe a flux lattice with square symmetry in the superconductor YNi{sub 2}B{sub 2}C when the applied field is parallel to the c-axis of the crystal. A square lattice observed previously in the isostructural magnetic analog ErNi{sub 2}B{sub 2}C was attributed to the interaction between magnetic order in that system and the flux lattice. Since the Y-based compound does not order magnetically, it is clear that the structure of the flux lattice is unrelated to magnetic order. In fact, they show that the flux lines have a square cross-section when the applied field is parallel to the c-axis of the crystal, since the measured penetration depth along the 100 crystal direction is larger than the penetration depth along the 110 by approximately 60%. This is the likely reason for the square symmetry of the lattice. Although they find considerable disorder in the arrangement of the flux lines at 2.5T, no melting of the vortex lattice was observed.
Date: December 1, 1997
Creator: Yethiraj, M.; Paul, D.M.; Tomy, C.V. & Forgan, E.M.
Partner: UNT Libraries Government Documents Department

THE SOLID SOLUBILITY AND CONSTITUTION OF YTTRIUM IN IRON-20 TO 40 w/o CHROMIUM ALLOYS

Description: The solid solubility of yttrium in iron-20 to 40 wt.% chromium alloys was determined by metallographic techniques and found to be extremely small. At 1320 deg C, the maximum solubility is about 0.12 wt. a yttrium. Study of iron- rich alloys of the iron-yttrium system shows that the compound YFe/sub 5/ exists. A eutectic occurs between iron and YFe/sub 5/ at 1257 deg C. The constitution of iron - 20 to 40 wt.% chromium-yttrium alloys ccntaining less than 6 wt.% yttrium was studied between 1250 and 600 deg C. It was found that, upon exceeding the solubility limit, YFe/sub 5/ is formed and cccurs in conjunction with alpha iron - chromium. At about 900 deg C and above 615 deg C, if more than 6 wt.% yttrium is present in the iron-35 wt.% chromium alloy and more than 3 wt. % in iron-40 wt.% chromium alloy, YFe/sub 4/ forms to give a three-phase field of alpha plus YFe/sub 5/ plus YFe/sub 4/. The upper yttrium limit of this phase field was not determined. At 815 deg C, sigma phase forms in the iron - chromium system and comes into equilibrium with YFe/sub 5/. (auth)
Date: October 20, 1959
Creator: Farkas, M.S. & Bauer, A.A.
Partner: UNT Libraries Government Documents Department

PREPARATION OF YTTRIUM FLUORIDE IN FLUIDIZED BEDS

Description: The batch fluid-bed hydrofluorination of yttrium oxide to yttrium fluoride of low residual oxygen content was studied in a 3-inch Monel column. Bed temperature, hydrofluorination time, and hydrofluoric acid excess were studied, and the contamination due to equipment corrosion was determined. A sample of the fluoride was converted to metal and analyzed for impurities. A brief investigation of the reaction kinetics was also made on the thermobalance. (auth)
Date: May 1, 1959
Creator: Knudsen, I.E. & Levitz, N.M.
Partner: UNT Libraries Government Documents Department

Sol-gel process for preparing YBa{sub 2}Cu{sub 4}O{sub 8} precursors from Y, Ba, and Cu acidic acetates/ammonia/ascorbic acid systems

Description: Sols were prepared by addition of ammonia to acidic acetate solutions of Y{sup 3+}, Ba{sup 2+}, and Cu{sup 2+}. Ascorbic acid was added to a part of the sol. The resultant sols were gelled to a shard, a film, or microspheres by evaporation at 60 C or by extraction of water from drops of emulsion suspended in 2-ethylhexanol-1. Addition of ethanol to the sols facilitated the formation of gel films, fabricated by a dipping technique, on glass or silver substrates. At 100 C, gels that were formed in the presence of ascorbic acid were perfectly amorphous, in contrast to the crystalline acetate gels. Conversion of the amorphous ascorbate gels to final products was easier than for the acetate gels. The quality of coatings prepared from ascorbate gels was superior to that of acetate gel coatings.
Date: August 1, 1995
Creator: Deptula, A.; Lada, W.; Olczak, T.; Goretta, K.C.; Di Bartolomeo, A. & Casadio, S.
Partner: UNT Libraries Government Documents Department

Dosimetry and quantitative radionuclide imaging in radioimmunotherapy: Final report, July 15, 1992-July 14, 1996

Description: Brief summaries of the principal accomplishments of this project on the development of quantitative SPECT for high energy photons (87Y, 19F) and stability testing of 87Y-labeled antibodies in the nude mouse model, development of an unified approach to photon and beta particle dosimetry, quantitative SPECT for nonuniform attenuation, and development of patient-specific dosimetry in radioimmunotherapy.
Date: September 1, 1996
Creator: Leichner, P.K.
Partner: UNT Libraries Government Documents Department

Inelastic neutron studies of the low energy phonon excitations in the RENi{sub 2}B{sub 2}C superconductors (RE = Lu, Y, Ho, Er)

Description: The authors studied the low-energy phonon excitations for wavevectors close to the Fermi surface nesting vector {rvec {xi}}{sub m} {approx_equal} 0.55{rvec a}. They find that above T{sub c} the frequencies of the {Delta}{sub 4} [{zeta}00] lowest-lying optical and acoustic phonon modes decrease with decreasing temperature, for {rvec {xi}} close to {rvec {xi}}{sub m}, and there is a shift of intensity from the upper to the lower mode, an effect characteristic of coupled modes. From approximately 120K down to temperatures in the vicinity of T{sub c}, only a single unresolved peak is observed. Below T{sub c} the phonon spectra of the Y and Lu compounds change dramatically: they consist of a sharp peak at approximately 4.5 meV with a weak shoulder at the higher energy side. No such sharp peak was observed below T{sub c} in the Ho and Er compounds.
Date: December 31, 1997
Creator: Bullock, M.; Stassis, C.; Zarestky, J.; Goldman, A.; Canfield, P.; Shirane, G. et al.
Partner: UNT Libraries Government Documents Department

Long Term Stability of Ceramics in Liquid Lithium

Description: Two candidate materials for insulating coatings in a lithium-cooled fusion reactor have been exposed to lithium in 1000 h isothermal tests from 400-800 C to determine their maximum compatibility temperature. Bulk samples of AlN + 5 wt%Y{sub 2}O{sub 3} showed significant mass loss at 600 C and higher temperatures. The amount of attack was reduced when AlN + 0.04 wt%Y was tested. Characterization by Auger spectroscopy of a AlN + 0.04 wt%Y specimen exposed at 600 C indicated the possibility of a lithium aluminate compound formation. Bulk, polycrystalline specimens of CaO (99.9% purity) showed mass losses above 500 C indicating a possible dissolution problem that had not been observed in previous short-term screening tests and is not predicted based on thermodynamic calculations. Doping of the lithium with oxygen (in the case of CaO) did not appear effective in reducing the mass loss at 600 C.
Date: October 22, 2001
Creator: Pint, B.A.
Partner: UNT Libraries Government Documents Department

Photo- and cathodoluminescence of hydrothermally synthesized Y{sub 3}Al{sub 5}O{sub 12}:Tb and NaY(WO{sub 4}){sub 2}:Tb

Description: Cathodoluminescent (CL) phosphors with improved low-voltage characteristics are needed for use in emissive flat panel displays. Conventional high-temperature methods for phosphor synthesis yield large polycrystalline grains that must be pulverized prior to screen deposition. Grinding has been implicated in reducing phosphor efficiency by causing surface contamination and defects. Hydrothermal synthesis has been used to improve the quality of ceramic powders by producing fine, well-formed crystallites without grinding. Two green-emitting phosphors, Y{sub 3}Al{sub 5}O{sub 12}:Tb (YAG:Tb) and NaY(WO{sub 4}){sub 2}:Tb, were used to test the effects of hydrothermal. synthesis on grain size and morphology, and on low-voltage CL properties. YAG:Th prepared hydrothermally consisted of submicron crystallites with a typical garnet habit. The CL efficiency of hydrothermally synthesized YAG:Tb (3 lm/W at 800 V) was comparable to that of equivalent YAG:Tb compositions prepared via high-temperature solid state reaction. In comparison, CL intensities of Gd{sub 3}Ga{sub 5}O{sub l2}:Tb were slightly better (3.5 lm/W at 800 V), while those of NaY(WO{sub 4}){sub 2}:Tb were approximately 1/100th that of YAG:Tb. Both CL and photoluminescence data show that the difference in the cathodoluminescence of YAG and NaY(WO{sub 4}){sub 2} can be understood in terms of differences in the mechanism of activation.
Date: October 1, 1995
Creator: Phillips, M.L.F. & Potter, B.G. Jr.
Partner: UNT Libraries Government Documents Department

Laser ablation plume thermalization dynamics in background gases: Combined imaging, optical absorption and emission spectroscopy, and ion probe measurements

Description: Combined diagnostic measurements are employed to characterize the penetration of energetic ablation plumes through background gases during a key transitional regime in which the ion flux is observed to split into distinct fast and slowed components. This apparently general phenomenon occurs over a limited range of distances at ambient pressures typically used for PLD (pulsed laser deposition) and may be important to film growth by PLD because a ``fast`` component of ions can arrive at the probe (or substrate) with little or no delay compared to propagation in vacuum. At longer distances, this ``fast`` component is completely attenuated, and only slowed distributions of ions are observed. Interestingly, this ``fast`` component is easily overlooked in imaging studies because the bright plume luminescence occurs in the slowed distribution. Time- and spatially-resolved optical absorption and emission spectroscopy are applied to experimentally determine the composition of the ``fast`` and ``slow`` propagating plume components for a single-component target ablation (yttrium) into an inert gas (argon) for correlation with quantitative imaging and ion probe measurements. The yttrium/argon system was chosen because optical absorption spectroscopy of both Y and Y+ was simultaneously possible and the inert nature of argon. Experimental results for several other systems, including Si/Ar, Si/He, YBCO/O{sub 2} are presented to illustrate variations in scattering mechanisms.
Date: February 1, 1995
Creator: Geohegan, D.B. & Puretzky, A.A.
Partner: UNT Libraries Government Documents Department