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Photodeposition of Pt on Colloidal CdS and CdSe/CdS Semiconductor Nanostructures

Description: Semiconductor photocatalysis has been identified as a promising avenue for the conversion of solar energy into environmentally friendly fuels, most notably by the production of hydrogen from water.[1-5] Nanometer-scale materials in particular have attracted considerable scientific attention as the building blocks for light-harvesting applications.[6,7] Their desirable attributes include tunability of the optical properties with size, amenability to relatively inexpensive low-temperature process… more
Date: August 6, 2008
Creator: Dukovic, Gordana; Merkle, Maxwell G.; Nelson, James H.; Hughes, Steven M. & Alivisatos, A. Paul
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Carbon Nanotube-Based Permeable Membranes

Description: A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium t… more
Date: April 6, 2004
Creator: Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T & Eaglesham, D
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Structure of Oxide Nanoparticles in Fe-16Cr MA/ODS Ferritic Steel

Description: Oxide nanoparticles in Fe-16Cr ODS ferritic steel fabricated by mechanical alloying (MA) method have been examined using high-resolution transmission electron microscopy (HRTEM) techniques. A partial crystallization of oxide nanoparticles was frequently observed in as-fabricated ODS steel. The crystal structure of crystalline oxide particles is identified to be mainly Y{sub 4}Al{sub 2}O{sub 9} (YAM) with a monoclinic structure. Large nanoparticles with a diameter larger than 20 nm tend to be in… more
Date: April 6, 2010
Creator: Hsiung, L; Fluss, M & Kimura, A
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Molecular beam epitaxy of GaNAs alloys with high As content for potential photoanode applications in hydrogen production

Description: The authors have succeeded in growing GaN1?xAsx alloys over a large composition range (0 < x < 0.8) by plasma-assisted molecular beam epitaxy. The enhanced incorporation of As was achieved by growing the films with high As{sub 2} flux at low (as low as 100 C) growth temperatures, which is much below the normal GaN growth temperature range. Using x-ray and transmission electron microscopy, they found that the GaNAs alloys with high As content x > 0.17 are amorphous. Optical absorption m… more
Date: October 6, 2009
Creator: Novikov, S. V.; Staddon, C. R.; Foxon, C. T.; Yu, K. M.; Broesler, R.; Hawkridge, M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

CHARACTERIZATION OF DWPF MELTER OFF-GAS QUENCHER AND STEAM ATOMIZED SCRUBBER DEPOSIT SAMPLES

Description: This report summarizes the results from the characterization of deposits from the inlets of the primary off-gas Quencher and Steam Atomized Scrubber (SAS) in the Defense Waste Processing Facility (DWPF), as requested by a technical assistance request. DWPF requested elemental analysis and compound identification to help determine the potential causes for the substance formation. This information will be fed into Savannah River National Laboratory modeling programs to determine if there is a way… more
Date: June 6, 2007
Creator: Zeigler, K & Ned Bibler, N
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The Effect of Solution Annealing on the Microstructural Behavior of Alloy 22 Welds

Description: Multi-pass gas tungsten arc welds of Alloy 22 were subjected to solution annealing durations of 20 minutes, 24 hours, 72 hours and 1 week at temperatures of 1075, 1121, 1200, and 1300 C. The specimens were studied in cross section by secondary electron microscopy to determine the effect of solution annealing on tetrahedrally close packed (TCP) precipitate stability. Electron backscatter diffraction mapping was also performed on all of the specimens to determine the recrystallization behavior of… more
Date: May 6, 2005
Creator: El-Dasher, B S; Edgecumbe, T S & Torres, S G
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

On the Micromechanisms of Anomalous Slip in BCC Metals

Description: Dislocation substructures developed in high-purity Mo single crystals deformed under uniaxial compression at room temperature to a total strain of {approx} 0.5% with a strain rate of 1 s{sup -1} have been investigated using transmission electron microscopy (TEM) techniques in order to elucidate the underlying micromechanisms of the anomalous operation of {l_brace}0{bar 1}1{r_brace} slip systems, i.e. Schmid-law violation, in bcc metals. The crystals were oriented with the stress axis parallel t… more
Date: September 6, 2005
Creator: Hsiung, L L
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Conditioning effects on La1-xSrxMnO3-Yttria stabilized Zirconia electrodes for thin-film solid oxide fuel cells

Description: Composite cathodes of 50/50 vol percent LSM-YSZ (La1-xSrxMnO3-yttria stabilized zirconia) were deposited onto dense YSZ electrolytes by a colloidal deposition technique. The cathode characteristics were then examined by scanning electron microscopy (SEM) and studied by an impedance spectroscopy (IS). Conditioning effects of the LSM-YSZ cathodes were seen, and remedies for these effects were proposed for improving the performance of a solid oxide fuel cell (SOFC). LSM surface contamination and m… more
Date: December 6, 2002
Creator: Lee, You-Kee; Kim, Jung-Yeul; Lee, Young-Ki; Kim, Insoo; Moon, Hee-Soo; Park, Jong-Wan et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Immobilization of AM-241, Formed Under Plutonium Metal Conversion into Monazite-Type Ceramics

Description: Lanthanum orthophosphate with the monazite structure was proposed on examinations as a suitable matrix for immobilization of future americium-containing liquid wastes, which could be formed in conversion of metallic plutonium into oxide at PA ''Mayak.'' Specimens of monazite non-active ceramics were fabricated from LaPOA powders obtained using a thin-film evaporator by either hot-pressing or cold-pressing and sintering at 900-1300 C. According to electron microprobe analysis (EMPA), scanning el… more
Date: June 6, 2001
Creator: Aloy, A. S.; Kovarskaya, E. N.; Koltsova, T. I.; Samoylov, S. E.; Rovnyi, S. I.; Medvedev, G. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

HRTEM Imaging of Atoms at Sub-Angstrom Resolution

Description: John Cowley and his group at Arizona State University pioneered the use of transmission electron microscopy (TEM) for high-resolution imaging. Images were achieved three decades ago showing the crystal unit cell content at better than 4 Angstrom resolution. This achievement enabled researchers to pinpoint the positions of heavy atom columns within the unit cell. Lighter atoms appear as resolution is improved to sub-Angstrom levels. Currently, advanced microscopes can image the columns of the li… more
Date: April 6, 2005
Creator: O'Keefe, Michael A.; Allard, Lawrence F. & Blom, Douglas A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Carbon Surface Layers on a High-Rate LiFePO4

Description: Transmission electron microscopy (TEM) was used to image particles of a high-rate LiFePO4 sample containing a small amount of in situ carbon. The particle morphology is highly irregular, with a wide size distribution. Nevertheless, coatings, varying from about 5-10 nm in thickness, could readily be detected on surfaces of particles as well as on edges of agglomerates. Elemental mapping using Energy Filtered TEM (EFTEM) indicates that these very thin surface layers are composed of carbon. These … more
Date: September 6, 2005
Creator: Gabrisch, Heike; Wilcox, James D. & Doeff, Marca M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Surface Studies of Ultra Strength Drilling Steel after Corrosion Fatigue in Simulated Sour Environment

Description: The Unites States predicted 60% growth in energy demand by 2030 makes oil and natural gas primary target fuels for energy generation. The fact that the peak of oil production from shallow wells (< 5000 m) is about to be reached, thereby pushing the oil and natural gas industry into deeper wells. However, drilling to depths greater than 5000 m requires increasing the strength-to weight ratio of the drill pipe materials. Grade UD-165 is one of the ultra- high yield strength carbon steels devel… more
Date: May 6, 2012
Creator: Ziomek-Moroz, M.; Hawk, J. A.; Ramgopal, Thodla & Gui, F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Towards Atomic Column-by-Column Spectroscopy

Description: The optical arrangement of the scanning transmission electron microscope (STEM) is ideally suited for performing analysis of individual atomic columns in materials. Using the incoherent Z-contrast image as a reference, and arranging incoherent conditions also for the spectroscopy, a precise correspondence is ensured between features in the inelastic image and elastic signals. In this way the exact probe position needed to maximise the inelastic signal from a selected column can be located and m… more
Date: September 6, 1998
Creator: Pennycook, S.J. & Rafferty, B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Use of strain-annealing to evolve the grain boundary character distribution in polycrystalline copper

Description: We have used a two-step (low and high temperature) strain-annealing process to evolve the grain boundary character distribution (GBCD) in fully recrystallized oxygen-free electronic (OFE) Cu bar that was forged and rolled. Orientation imaging microscopy has been used to characterize the GBCD after each step in the processing. The fraction of special grain boundaries was {similar_to}70% in the starting recrystallized material. Three different processing conditions were employed: high, moderate, … more
Date: November 6, 1996
Creator: King, W.E. & Schwartz, A.J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Composition Effects on Aluminide Oxidation Performance: Objectives for Improved Bond Coats

Description: Formerly, the role of metallic coatings on Ni-base superalloys was simply to limit environmental attack of the underlying substrate. However, a new paradigm has been established for metallic coatings adapted as bond coats for thermal barrier coatings. It is no longer sufficient for the coating to just minimize the corrosion rate. The metallic coating must also form a slow-growing external Al{sub 2}O{sub 3} layer beneath the overlying low thermal conductivity ceramic top coat. This thermally gro… more
Date: September 6, 2001
Creator: Pint, BA
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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TEM investigation of a ceramic waste form for immobilization of process salts generated during electrometallurgical treatment of spent nuclear fuel.

Description: Transmission electron microscopy (TEM) examination is presented of the microstructure of a ceramic waste form developed at Argonne National Lab - West for immobilization of actinides and fission products present in an electrorefiner salt. The material is produced by occluding the salt in zeolite granules, followed by hot isostatic pressing of the occluded zeolite in a mixture with a borosilicate glass. The paper presents results from a cold surrogate ceramic waste form, as well as {sup 239}Pu a… more
Date: May 6, 1999
Creator: Esh, D. W.; Frank, S. M.; Goff, K. M.; Johnson, S. G.; Moschetti, T. L.; O'Holleran, T. P. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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