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20030022660 NASA Glenn Research Center, Cleveland, OH, USA
Synthesis,and structural characterization of [(CH3(C5H4N))Ga(SCH2(CO)O)]-[(4-MepyH)]+, a novel Ga(III) five
coordinate complex.
Banger, Kulbinder K.; Duraj, Stan A.; Fanwic, Phillp E.; Hepp, Aloysius F.; Martuch, Robert A.; January 2003; 12 pp.; In
English
Contract(s)/Grant(s): NCC3-318; NCC3-162; NCC3-246; RTOP 755-60-01; No Copyright; Avail: CASI; A03, Hardcopy
The synthesis and structural characterization of a novel ionic Ga(III) five coordinate complex
[{CH3(C5H4N)}Ga(SCH2(CO)O)2]-[(4-MepyH)]+, (4-Mepy = CH3(C5H5N)) from the reaction between Ga2Cl4 with
sodium mercapto-acetic acid in 4-methylpyridine is described. Under basic reaction conditions the mercapto ligand is found
to behave as a 2e- bidentate ligand. Single crystal X-ray diffraction studies show the complex to have a distorted square
pyramidal geometry with the [(-SCH2(CO)CO-)] ligands in a trans conformation. The compound crystallizes in the P2(sub
1)/c (No. 14) space group with a = 7.7413(6) A, b = 16.744(2) A, c = 14.459(2) A, V = 1987.1(6) A(sup 3), R(F) = 0.032 and
R(sub w) = 0.038.
Author
Acetic Acid; Sodium; Thiols; Synthesis (Chemistry); Ions; Chemical Reactions
20030025402 NASA Glenn Research Center, Cleveland, OH, USA National Center for Microgravity Research on Fluids
and Combusiton, Cleveland, OH, USA
Carbon Nanostructure Examined by Lattice Fringe Analysis of High Resolution Transmission Electron Microscopy
Images
VanderWal, Randy L.; Tomasek, Aaron J.; Street, Kenneth; Thompson, William K.; November 02, 2002; 22 pp.; In English;
Original contains black and white illustrations
Contract(s)/Grant(s): NRA-99-HEDs-01; NCC3-975; WBS 22-101-12-15; No Copyright; Avail: CASI; A03, Hardcopy
The dimensions of graphitic layer planes directly affect the reactivity of soot towards oxidation and growth. Quantification
of graphitic structure could be used to develop and test correlations between the soot nanostructure and its reactivity. Based
upon transmission electron microscopy images, this paper provides a demonstration of the robustness of a fringe image
analysis code for determining the level of graphitic structure within nanoscale carbon, i.e. soot. Results, in the form of
histograms of graphitic layer plane lengths, are compared to their determination through Raman analysis.
Author
Carbon; High Resolution; Nanostructure (Characteristics); Transmission Electron Microscopy; Image Analysis; Raman
Spectroscopy
20030032235 NASA Glenn Research Center, Cleveland, OH, USA
Homoepitaxial ‘Web Growth’ of SiC to Terminate C-Axis Screw Dislocations and Enlarge Step-Free Surfaces
Neudeck, Philip G.; Powell, J. Anthony; Trunek, Andrew; Spry, David; Beheim, Glenn M.; Benavage, Emye; Abel, Phillip;
Vetter, William M.; Dudley, Michael, Trans ; Materials Science Forum; 2002; Volumes 389-393, pp. 251-254; In English;
International Conference on Silicon Carbide and Related Materials 2001, 28 Oct. - 2 Nov. 2001, Tsukuba, Japan; Original
contains black and white illustrations; Copyright; Avail: Other Sources
Homoepitaxial Chemical Vapor Deposition (CVD) growth of thin lateral cantilevers emanating from the edges of mesa
patterns dry-etched into on-axis commercial 4H-SiC substrates prior to growth is reported. Cantilevers on the order of a
micrometer thick extending tens of micrometers from the edge of a mesa have been grown. The termination of vertically
propagating screw dislocations, including a micropipe, that are overgrown by the cantilevers has been demonstrated, in large
part because the crystal structure of the cantilevers is established laterally from the mesa sidewalls. This technique could help
reduce performance-degrading dislocations in SiC electrical devices.
Author
Silicon Carbides; Epitaxy; Vapor Deposition; Crystal Growth
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