The Effect of Dopant Additions on the Microstructure of Boron Fibers Before and After Reaction to MgB2

2004 ◽  
Vol 848 ◽  
Author(s):  
James V. Marzik ◽  
Raymond J. Suplinskas ◽  
William J. Croft ◽  
Warren J. MoberlyChan ◽  
John D. DeFouw ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Elevated Temperatures ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Boron Fiber ◽  
Transmission Electron ◽  
Before And After ◽  
Fiber Metal ◽  
Molten Magnesium

ABSTRACTBoron fibers made by a commercial chemical vapor deposition (CVD) process have been used as precursors for the formation of magnesium diboride (MgB2) superconducting wires. Prior to a reaction with magnesium, the addition of dopants such as carbon and titanium to the boron fiber has been shown to enhance the superconducting properties of MgB2. These dopants also influence the kinetics of the reaction with magnesium. In this study, the effect of carbon dopant additions on the microstructure of boron fibers was investigated using powder x-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Additionally, bundles of boron fibers were pressure infiltrated with molten magnesium and reacted at elevated temperatures. The microstructure and microchemistry of the fiber-metal interfaces were investigated by TEM and energy dispersive x-ray analysis (EDS).

Synthesis of Crystalline C3N4 films and the new C-N Phases

1996 ◽  
Vol 441 ◽  
Author(s):  
Yan Chen ◽  
D. J. Johnson ◽  
R. H. Prince ◽  
Liping Guo ◽  
E. G. Wang
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Growth Parameters ◽  
Chemical Vapor ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Transmission Electron ◽  
Hot Filament

AbstractCrystalline C-N films composed of α- and β-C3N4, as well as other C-N phases, have been synthesized via bias-assisted hot-filament chemical vapor deposition using a gas mixture of nitrogen and methane. Scanning electron microscopy(SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the films. Lattice constants of the α- and β-C3N4 phases obtained coincide very well with the theoretical values. In addition to these phases, two new C-N phases in the films have been identified by TEM and XRD; one having a tetragonal structure with a = 5.65 Å, c = 2.75Å, and the second having a monoclinic structure with a = 5.065 Å, b= 11.5 Å, c = 2.801 Å and β = 96°. Their stoichiometric values and atomic arrangements have not yet been identified. Furthermore, variation in growth parameters, for example methane concentration, bias voltage, etc., can yield preferred growth of different C-N phases.

scholarly journals Structural Property Study for GeSn Thin Films

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3645
Author(s):  
Liyao Zhang ◽  
Yuxin Song ◽  
Nils von den Driesch ◽  
Zhenpu Zhang ◽  
Dan Buca ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron

The structural properties of GeSn thin films with different Sn concentrations and thicknesses grown on Ge (001) by molecular beam epitaxy (MBE) and on Ge-buffered Si (001) wafers by chemical vapor deposition (CVD) were analyzed through high resolution X-ray diffraction and cross-sectional transmission electron microscopy. Two-dimensional reciprocal space maps around the asymmetric (224) reflection were collected by X-ray diffraction for both the whole structures and the GeSn epilayers. The broadenings of the features of the GeSn epilayers with different relaxations in the ω direction, along the ω-2θ direction and parallel to the surface were investigated. The dislocations were identified by transmission electron microscopy. Threading dislocations were found in MBE grown GeSn layers, but not in the CVD grown ones. The point defects and dislocations were two possible reasons for the poor optical properties in the GeSn alloys grown by MBE.

Effect of Precursor Salt on FeP Nanoparticle Formation

2002 ◽  
Vol 755 ◽  
Author(s):  
Susanthri C. Perera ◽  
Stephanie L. Brock
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Elevated Temperatures ◽  
Trioctylphosphine Oxide ◽  
X Ray Diffraction ◽  
Iron Salt ◽  
X Ray ◽  
Transmission Electron ◽  
Initial Iron

ABSTRACTThe formation of single phase FeP nanocrystals has been achieved by the reaction of Fe(III) salts (iron(III)acetylacetonate (Fe(acac)3) and iron(III)chloride (FeCl3)) with tris(trimethylsilyl)phosphine in trioctylphosphine oxide (TOPO)/trioctylphosphine (TOP) at elevated temperatures. The sizes of nanoparticles formed differ markedly depending on the initial iron salt used. Use of Fe(acac)3 always resulted in comparatively bigger particle formation (∼5 nm) while FeCl3 forms much smaller particles (∼1 nm) as confirmed by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).

Growth and characterization of type II ZnO/ZnSe core/shell nanowire arrays

2010 ◽  
Vol 25 (7) ◽  
pp. 1272-1277 ◽  
Author(s):  
Jinjian Zheng ◽  
Zhiming Wu ◽  
Weihuang Yang ◽  
Shuping Li ◽  
Junyong Kang
Keyword(s):  
Electron Microscopy ◽  
Chemical Vapor ◽  
Band Alignment ◽  
Nanowire Arrays ◽  
Core Shell ◽  
Type Ii ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Potential Applications

Type II ZnO/ZnSe core/shell nanowire arrays were grown by a two-step chemical vapor deposition. The nanowire arrays with dense nanoislands on the surface are well aligned and normal to the substrate imaged by scanning electron microscopy. The core/shell structure of nanowires was identified by a high-resolution transmission electron microscopy. The structure and composition of the shell were confirmed to be wurtzite ZnSe by x-ray diffraction, Raman scattering and energy-dispersive x-ray spectroscopy. Moreover, an intense emission was observed at 1.89 eV smaller than the band gaps of core and shell materials by photoluminescence, indicating the achievement of the type II band alignment at the interface. This study is expected to contribute to the potential applications in novel photovoltaic devices.

scholarly journals Metal film deposition by laser breakdown chemical vapor deposition

1986 ◽  
Vol 1 (3) ◽  
pp. 420-424 ◽  
Author(s):  
T.R. Jervis ◽  
L.R. Newkirk
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Film Deposition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

Dielectric breakdown of gas mixtures can be used to deposit thin films by chemical vapor deposition with appropriate control of flow and pressure conditions to suppress gas-phase nucleation and particle formation. Using a pulsed CO2 laser operating at 10.6 μ where there is no significant resonant absorption in any of the source gases, homogeneous films from several gas-phase precursors have been sucessfully deposited by gas-phase laser pyrolysis. Nickel and molybdenum from the respective carbonyls representing decomposition chemistry and tungsten from the hexafluoride representing reduction chemistry have been demonstrated. In each case the gas precursor is buffered with argon to reduce the partial pressure of the reactants and to induce breakdown. Films have been characterized by Auger electron spectroscopy, x-ray diffraction, transmission electron microscopy, pull tests, and resistivity measurements. The highest quality films have resulted from the nickel depositions. Detailed x-ray diffraction analysis of these films yields a very small domain size consistent with the low temperature of the substrate and the formation of metastable nickel carbide. Transmission electron microscopy supports this analysis.

Reduction of Structural Defects in Ge Epitaxially Grown on Nano-Structured Si Islands on SOI Substrate

2013 ◽  
Vol 205-206 ◽  
pp. 400-405
Author(s):  
Peter Zaumseil ◽  
Yuji Yamamoto ◽  
Markus Andreas Schubert ◽  
Thomas Schroeder ◽  
Bernd Tillack
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Strain State ◽  
Chemical Vapor ◽  
Structural Defects ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Nanostructured Si

One way to further increase performance and/or functionality of Si micro-and nanoelectronics is the integration of alternative semiconductors on silicon (Si). We studied the Ge/Si heterosystem with the aim to realize a Ge deposition free of misfit dislocations and with low content of other structural defects. Ge nanostructures were selectively grown by chemical vapor deposition on periodic Si nanoislands (dots and lines) on SOI substrate either directly or with a thin (about 10 nm) SiGe buffer layer. The strain state of the structures was measured by different laboratory-based x-ray diffraction techniques. It was found that a suited SiGe buffer improves the compliance of the Si compared to direct Ge deposition; plastic relaxation during growth can be prevented, and fully elastic relaxation of the structure can be achieved. Transmission electron microscopy confirms that the epitaxial growth of Ge on nanostructured Si is free of misfit dislocations.

scholarly journals Grain Structure and Growth of Dispersed Phase BN-AlN Coatings Grown via Chemical Vapor Deposition

1990 ◽  
Vol 202 ◽  
Author(s):  
Garth B. Freeman ◽  
Woo Y. Lee ◽  
W. J. Lackey ◽  
John A. Hanigofsky ◽  
Karren More
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Ceramic Coatings ◽  
Grain Structure ◽  
Dispersed Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

ABSTRACTThis paper discusses the variation in microstructures encountered during the separate depositions of boron nitride (BN) and aluminum nitride (A1N) as well as during the codeposition of BNߝA1N dispersed phase ceramic coatings. This combination was chosen in order to take advantage of the self lubricating properties of hexagonal BN along with the hard, erosion resistance of A1N. Films were characterized using scanning and transmission electron microscopy (SEM and TEM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction (XRD).A range of coating microstructures are possible depending on the conditions of deposition. The best films produced, in terms of hardness, density, and tenacity, were a fine mixture of turbostratic BN and preferentially oriented A1N whiskers aligned with the whisker axis perpendicular to the substrate surface as seen by both electron microscopy and x-ray diffraction.

Growth and Photoluminescence of β-SiC Nanowires on Porous Silicon Array

2013 ◽  
Vol 662 ◽  
pp. 11-15
Author(s):  
Hai Yan Wang ◽  
Li Ping Kang ◽  
Yong Qiang Wang ◽  
Zi Jiong Li
Keyword(s):  
Electron Microscopy ◽  
Porous Silicon ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Method ◽  
Fluorescent Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sic Nanowires ◽  
Quantum Confinement Effects ◽  
Transmission Electron

Nonaligned and curly β-SiC nanowires (nw-SiC) were grown on porous silicon array (PSA) by a chemical vapor deposition method with nickel as the catalyst. The morphology, structure and the composition of the nw-SiC/PSA and the SiC-SiO2core-shell fibers which is the semi-product were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Based on the experimental results a possible growth mechanism of nw-SiC was explained. Two broad photoluminescence peaks located around ~409 and ~494 nm were observed in nw-SiC/PSA in the PL measurement when utilizing 300 nm ultraviolet fluorescent light excited at room temperature. The excellent luminescent performances are ascribed to the quantum confinement effects in nw-SiC. The optical merits of nw-SiC/PSA made it a promising material in the fields of ultraviolet-blue emitting devices.

Polymorphous silicon nanowires synthesized by plasma-enhanced chemical vapor deposition

2002 ◽  
Vol 737 ◽  
Author(s):  
X.B. Zeng ◽  
X.B. Liao ◽  
H.W. Diao ◽  
Z.H. Hu ◽  
Y.Y. Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Silicon Nanowires ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
The Body ◽  
Si Nanowires ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

ABSTRACTPolymorphous Si nanowires (SiNWS) have been successfully synthesized on Si wafer by plasma enhanced chemical vapor deposition (PECVD) at 440°C, using silane as the Si source and Au as the catalyst. To grow the polymorphous SiNWS preannealing the Si substrate with Au film at 1100 °C is needed. The diameters of Si nanowires range from 15 to 100 nm. The structure, morphology and chemical composition of the SiNWS have been characterized by high resolution x-ray diffraction, scanning electron microscopy, transmission electron microscopy, as well as energy dispersive x-ray spectroscopy. A few interesting nanowires with Au nanoclusters uniformly distributed in the body of the wire were also produced by this technique.

SYNTHESIS OF HIGH QUALITY CRYSTALLINE C-N FILMS ON SILICON

1996 ◽  
Vol 10 (12) ◽  
pp. 567-571 ◽  
Author(s):  
YAN CHEN ◽  
E.G. WANG ◽  
FENG CHEN ◽  
LIPING GUO
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Interfacial Layer ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Transmission Electron ◽  
Hot Filament ◽  
Microscopy Images

High quality crystalline C–N films have been synthesized via hot filament chemical vapor deposition using a gas mixture of nitrogen and methane. Scanning electron microscopy images show that a high density of crystalline clusters has been achieved. The clusters are composed of small columnar crystals (20–200 nm across) with hexagonal facets. Energy dispersive X ray analysis indicates a relative nitrogen:carbon composition of 1.30–2.5. X ray diffraction results indicate the films composed of β- and α- C 3 N 4 phases. Together with transmission electron microscopy analyses, we suggest that an interfacial layer C 3−x Si x N 4 is formed between the silicon substrate and the crystalline carbonnitride films.

Sign in / Sign up

Export Citation Format

Share Document