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Gelcasting of aluminum titanate. Final report

Description: This Cooperative Research and Development Agreement (CRADA) was undertaken to assess the applicability of the gelcasting process for forming automotive exhaust port liner green bodies using Golden Technologies` proprietary aluminum titanate powder composition. A gelcasting process, specifically tailored to Golden Technologies` powder, was developed and used successfully to form green bodies for property evaluation. Using appropriate milling and firing conditions, it was found that the gelcast m… more
Date: August 1, 1997
Creator: Nunn, S.D. & Stephan, J.E.
Partner: UNT Libraries Government Documents Department
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Inductively Coupled Plasma Etching in ICl- and IBr-Based Chemistries: Part I. GaAs, GaSb and AlGaAs

Description: High density plasma etching of GaAs, GaSb and AIGaAs was performed in IC1/Ar and lBr/Ar chemistries using an Inductively Coupled Plasma (ICP) source. GaSb and AlGaAs showed maxima in their etch rates for both plasma chemistries as a function of interhalogen percentage, while GaAs showed increased etch rates with plasma composition in both chemistries. Etch rates of all materials increased substantially with increasing rf chuck power, but rapidly decreased with chamber pressure. Selectivities > … more
Date: November 23, 1998
Creator: Abernathy, C.R.; Cho, H.; Hahn, Y.B.; Hays, D.C.; Hobson, W.S.; Jung, K.B. et al.
Partner: UNT Libraries Government Documents Department
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Reactive Ion Beam Etching of GaAs and Related Compounds in an Inductively Coupled Plasma of Cl(2)-Ar Mixture

Description: Reactive ion beam etching (RD3E) of GaAs, GaP, AIGaAs and GaSb was performed in a Cl2-Ar mixture using an Inductively Coupled Plasma (ICP) source. `The etch rates and yields were strongly affected by ion energy and substrate temperature. The RJBE was dominated by ion-assisted etching at <600 eV and by physical sputtering beyond 600 eV. The temperature dependence of the etch rates revealed three different regimes, depending on the substrate temperature: 1) sputtering-etch limited, 2) products-re… more
Date: November 23, 1998
Creator: Abernathy, C. R.; Hahn, Y. B.; Hays, D.; Lambers, E. S.; Lee, J. W.; Pearton, S. J. et al.
Partner: UNT Libraries Government Documents Department
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Determination of site-occupancies in aluminide intermetallics by ALCHEMI

Description: The site-distributions of Fe in four B2-ordered NiAl-based alloys with Fe concentrations of 10%, 2%, and 0.5% have been determined by ALCHEMI (atom-location by channeling-enhanced microanalysis). Site-distributions have been extracted with standard errors between {approximately} 1.5% (10% Fe concentration) and {approximately} 6% (0.5% Fe concentration). The results show that Fe has no strong site-preference in NiAl and tends to reside on the site of the stoichiometrically deficient host element… more
Date: April 1, 1995
Creator: Anderson, I. M.; Bentley, J. & Duncan, A. J.
Partner: UNT Libraries Government Documents Department
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Reducing polarization dependence in asymmetric coupler wavelength filters using birefringence compensation

Description: We demonstrate that a novel birefringence compensation technique can reduce the polarization dependence of AlGaAs directional coupler wavelength filters operating at {lambda} = 773 nm.
Date: October 1, 1994
Creator: Deri, R. J.; Emanuel, M. A.; Patterson, F. G. & Dijaili, S. P.
Partner: UNT Libraries Government Documents Department
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III-Sb (001) growth surfaces: Structure and island nucleation

Description: The authors have determined the reconstructions present on AlSb and GaSb(001) under conditions typical for device growth by molecular beam epitaxy. Within the range of Sb flux and temperature where the diffraction pattern is nominally (1 x 3), three distinct (4 x 3) reconstructions actually occur. The three structures are different than those previously proposed for these growth conditions, with two incorporating mixed III-V dimers on the surface. The presence of these hetero-dimers in the top … more
Date: April 24, 2000
Creator: Barvoso-Carter, W.; Bracker, A. S.; Culbertson, J. C.; Nosho, B. Z.; Shanabrook, B. V.; Whitman, L. J. et al.
Partner: UNT Libraries Government Documents Department
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Advance concepts for conversion of syngas to liquids. Quarterly report No. 3, April 29, 1995--July 28, 1995

Description: The aim of this phase of our study is to demonstrate how cobalt-containing aluminophosphate molecular sieves with structure types AFI and AEL can be synthesized from a clear homogeneous solution. The advantage of beginning with a clear solution is that transient phases, either crystalline or amorphous, can be more easily identified. The nature of these phases and their role in the crystallization process can be seen more easily. HF is used as a mineralizing agent. It has been reported that the … more
Date: December 1, 1995
Creator: Szostak, R.; Abotsi, G. & Mitchell, M.
Partner: UNT Libraries Government Documents Department
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POC-scale testing of an advanced fine coal dewatering equipment/technique: Quarterly technical progress report,January--March 1997

Description: Laboratory centrifugal dewatering tests were conducted to study the effects of anionic and cationic flocculants on filtration of PMCC compliance (low sulfur) and non-compliance (high sulfur) ultrafine coal slurry. The results obtained with compliance coal indicated that use of 30 g/t anionic flocculant reduced filter cake moisture from 32. 3 to 29.0 percent and increased solids recovery by two absolute percentage points. Use of cationic flocculant had no effects on solids recovery but lowered c… more
Date: May 7, 1997
Creator: Tao, D.; Grappo, J. G. & Parekh, B. K.
Partner: UNT Libraries Government Documents Department
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Local vibrational modes of Se-H complexes in AlSb

Description: Using infrared spectroscopy the authors have observed local vibrational modes (LVMs) arising from Se-H complexes in AlSb. At liquid-helium temperatures, hydrogenated AlSb:Se samples have three stretch mode peaks at 1,606.3, 1,608.6, and 1,615.7 cm{sup {minus}1}, whereas deuterated samples have only one peak at 1,173.4 cm{sup {minus}1}. The anomalous splitting of the se-H stretch mode may be explained by a resonance between the stretch mode and two multi-phonon modes. As the temperature or press… more
Date: September 1, 1996
Creator: McCluskey, M. D.; Hsu, L.; Haller, E. E.; Walukiewicz, W. & Becla, P.
Partner: UNT Libraries Government Documents Department
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Investigation of the Effect of Microstructure on the R-Curve Behavior of Metal-Ceramic Composites

Description: An investigation was made into the effect of microstructure on the peak toughness and shape of the crack growth resistance curves for two ceramic-metal composites. An Al{sup 2}O{sup 3}/Al composite formed by Reactive Metal Penetration was used along with an AlN/Al composite formed using a reactive infiltration technique. The results indicate that the toughness increases with an increase in the volume fraction of the metal phase for a particular composite composition, and the peak toughness and … more
Date: July 1, 1995
Creator: Ellerby, Donald T.; Flinn, Brian D.; Scott, William D.; Bordia, Rajendra K.; Ewsuk, Kevin G.; Loehman, Ronald E. et al.
Partner: UNT Libraries Government Documents Department
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Development of Precipitated Iron Fischer-Tropsch Catalysts.

Description: Four (alumina or silica) supported catalysts with nominal compositions (on mass basis) of synthesized catalysts are: (1) 100 Fe/5 Cu/6 K/139 SiO{sub 2} (2) 100 Fe/10 Cu/6 K/134 SiO{sub 2}, (3) 100 Fe/5 Cu/ K/139 Al{sub 2}0{sub 3} and (4) 100 Fe/10 Cu/6 K/134 Al{sub 2}0{sub 3} were char BET surface area measurements. The surface areas of all four catalysts are between 94 and 136 m{sup 2}/g, whereas the surface areas of alumina and silica support are 213 and 252 m{sup 2}/g, respectively. The decr… more
Date: August 29, 1997
Creator: Bukur, D. B.; Ding, Y. & Chokkaram, S.
Partner: UNT Libraries Government Documents Department
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Microstructural and mechanical characterization of alumina scales thermally developed on iron aluminide alloys

Description: To understand the underlying phenomena when characterizing material performance, we must know the chemistry and physics of the early stages of oxidation, chemistry, and bonding at the substrate/oxide interface, effect of segregants on the strength of bonding, transport processes through the scale formed during corrosion, mechanisms of residual stress generation and relief, and fracture behavior at the oxide/substrate interface. Specific objectives of the program described here are to (a) system… more
Date: November 1996
Creator: Natesan, K.; Renusch, D.; Veal, B. W. & Grimsditch, M.
Partner: UNT Libraries Government Documents Department
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Borohydride reduction: A technique to synthesize nanosize transition metal oxides and nanocomposites

Description: This paper summarizes recent studies of using borohydride reduction to synthesize W, transition metal oxides such as WO{sub 2} and MoO{sub 2}, and Fe-Al{sub x}B{sub y}O{sub z}
Date: June 1, 1996
Creator: Zhu, Yuntian T.; Lowe, Terry C.; Stout, Michael G.; Manthiram, A. & Guggilla, S.
Partner: UNT Libraries Government Documents Department
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Attempt to control the interfacial strength

Description: Composites consisting of a B2 iron aluminide matrix and 40 vol.% of TiB{sub 2} particles were processed by liquid phase sintering. In order to encourage segregation of B or Ti at the FeAl/TiB{sub 2} interfaces, the iron aluminide matrix was microalloyed with B or Ti, respectively. Additions of Ti degraded the mechanical properties. However, for composites microalloyed with B, room temperature flexure tests show slight increases in the maximum strength (from 1250 to 1380 MPa) and the fracture to… more
Date: November 1, 1997
Creator: Schneibel, J.H. & Subramanian, R.
Partner: UNT Libraries Government Documents Department
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Inorganic-organic composite nanoengineered films using self-assembled monolayers for directed zeolite film growth

Description: This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Zeolites, or molecular sieves, are aluminosilicate cage structures that are typically grown from a heterogeneous mixture of organic template molecules, inorganic salts of alumina and silica, and water. These zeolites are used in industry for catalytic cracking of hydrocarbons (gasoline manufacture from oil), and contaminant removal from chemical produ… more
Date: October 1, 1997
Creator: Dye, R.C.; Hermes, R.E.; Martinez, M.G. & Peachey, N.M.
Partner: UNT Libraries Government Documents Department
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Scoping corrosion tests on candidate waste package basket materials for the Yucca Mountain Project

Description: A scoping corrosion test was performed on candidate waste package basket materials. The corrosion medium was a pH-buffered solution of chemical species expected to be produced by radiolysis. The test was conducted at 90{degrees}C for 96 hours. Samples included aluminum-, copper-, stainless steel-, and zirconium-based metallic materials and several ceramics, incorporating neutron-absorbing elements. Sample weight losses and solution chemical changes were measured. Both corrosion of the host mate… more
Date: March 1, 1998
Creator: Van Konynenburg, R. A.; Curits, P. C. & Summers, T. S. E.
Partner: UNT Libraries Government Documents Department
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Vertical cavity surface emitting lasers emitting near 1.5 {mu}m with Sb-based reflectors

Description: We describe use of AlAsSb/AlGaAsSb lattice matched to InP for distributed Bragg reflectors. These structures are integral to several surface normal devices, in particular vertical cavity surface emitting lasers. The high refractive index ratio of these materials allows formation of a highly reflective mirror with relatively few mirror pairs. As a result, we have been able to show for the first time the 77K CW operation of an optically pumped, monolithic, all-epitaxial vertical cavity laser, emi… more
Date: April 1, 1998
Creator: Blum, O.; Klem, J. F. & Vawter, G. A.
Partner: UNT Libraries Government Documents Department
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Construction of artificial pigment-protein antennae

Description: Photosynthesis is a complex process which results in the conversion of solar radiation into chemical energy. This chemical energy is then used as the free energy source for all living organisms. In its basic form, photosynthesis can be described as the light-activated synthesis of carbohydrates from the simple molecules of water and carbon dioxide: 6H{sub 2}O + 6 CO{sub 2} light C{sub 6}H{sub 12}O{sub 6} + 6 O{sub 2} This basic mechanism actually requires numerous reaction steps. The two primar… more
Date: January 10, 1997
Creator: Sibbald, J.
Partner: UNT Libraries Government Documents Department
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Pressure dependence of Se absorption lines in AlSb

Description: Using far infrared absorption spectroscopy, the authors have investigated electronic transition spectra of Se donors in AlSb as a function of hydrostatic pressure. At least two distinct ground to bound excited state transition lines, which depend quadratically on the pressure, can be seen. At pressures between 30 and 50 kbar, evidence of an anti-crossing between one of the electronic transitions and a peak which they attribute to the 2 zone center LO phonon mode can be seen.
Date: September 1, 1996
Creator: Hsu, L.; Haller, E.E. & Ramdas, A.K.
Partner: UNT Libraries Government Documents Department
open access

Effects of high temperature surface oxides on room temperature aqueous corrosion and environmental embrittlement of iron aluminides

Description: Studies were conducted to determine the effects of high-temperature surface oxides, produced during thermomechanical processing, heat treatment (750 {degrees}C in air, one hour) or simulated in-service-type oxidation (1000{degrees}C in air, 24 hours) on the room-temperature aqueous-corrosion and environmental-embrittlement characteristics of iron aluminides. Materials evaluated included the Fe{sub 3}Al-based iron aluminides, FA-84, FA-129, FAL and FAL-Mo, a FeAl-based iron aluminide, FA-385, an… more
Date: September 1, 1996
Creator: Buchanan, R. A. & Perrin, R. L.
Partner: UNT Libraries Government Documents Department
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