Microstructural Evaluation of Silicon Carbide Whisker Reinforced Alumina Fabricated with Carbon-Coated Whiskers

1991 ◽  
Vol 49 ◽  
pp. 920-921
Author(s):  
K. B. Alexander ◽  
P. F. Becher
Keyword(s):  
Silicon Carbide ◽  
High Resolution Electron Microscopy ◽  
Ceramic Composites ◽  
Interface Debonding ◽  
Resolution Electron ◽  
Microstructural Evaluation ◽  
Carbon Coated ◽  
Electron Energy Loss ◽  
Interfacial Films ◽  
Debonding Process

The presence of interfacial films at the whisker-matrix interface can significantly influence the fracture toughness of ceramic composites. The film may alter the interface debonding process though changes in either the interfacial fracture energy or the residual stress at the interface. In addition, the films may affect the whisker pullout process through the frictional sliding coefficients or the extent of mechanical interlocking of the interface due to the whisker surface topography.Composites containing ACMC silicon carbide whiskers (SiCw) which had been coated with 5-10 nm of carbon and Tokai whiskers coated with 2 nm of carbon have been examined. High resolution electron microscopy (HREM) images of the interface were obtained with a JEOL 4000EX electron microscope. The whisker geometry used for HREM imaging is described in Reference 2. High spatial resolution (< 2-nm-diameter probe) parallel-collection electron energy loss spectroscopy (PEELS) measurements were obtained with a Philips EM400T/FEG microscope equipped with a Gatan Model 666 spectrometer.

Microstructure and Microchemistry of Interfaces in Structural Ceramic Composites

1996 ◽  
Vol 458 ◽  
Author(s):  
K. B. Alexander ◽  
P. F. Becher ◽  
P. M. Rice ◽  
D. Braski ◽  
E. Y. Sun
Keyword(s):  
Silicon Nitride ◽  
High Resolution Electron Microscopy ◽  
Ceramic Composites ◽  
Silicon Nitride Ceramic ◽  
Resolution Electron ◽  
Phase Chemistry ◽  
Electron Energy Loss ◽  
Ceramic Interfaces ◽  
Composite Interfaces

ABSTRACTThe performance of reinforced ceramics, particularly the toughness and creep resistance, is often determined by the nature of the interface between the reinforcement and the ceramic matrix. Specially-designed experiments to investigate the role of the interfacial characteristics on toughening mechanisms and crack propagation in reinforced (silicon carbide whisker reinforced alumina) and self-reinforced (silicon nitride) ceramic composites will be described. In the whisker-reinforced composites, the interfacial topography and chemistry were of primary importance, whereas in the silicon nitride materials the formation of interfacial phases and glassy-phase chemistry influenced the interfacial debonding process. The composite interfaces were characterized by high resolution electron microscopy and high spatial resolution microchemical analysis, including energy-dispersive X-ray and electron energy loss spectroscopy. Results from energy-filtered images from ceramic interfaces will also be shown.

TEM Studies and Contact Resistance of Au/Ni/Ti/Ta/n-GaN Ohmic Contacts

2003 ◽  
Vol 764 ◽  
Author(s):  
D.N. Zakharov ◽  
Z. Liliental-Weber ◽  
A. Motayed ◽  
S.N. Mohammad
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
High Resolution Electron Microscopy ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Resolution Electron ◽  
Order Of Magnitude ◽  
Contact Surfaces ◽  
Electron Energy Loss ◽  
Magnitude Difference

AbstractOhmic Ta/Ti/Ni/Au contacts to n-GaN have been studied using high resolution electron microscopy (HREM), energy dispersive X-ray spectrometry (EDX) and electron energy loss spectrometry (EELS). Two different samples were used: A - annealed at 7500C withcontact resistance 5×10-6 Ω cm2 and B-annealed at 7750C with contact resistance 6×10-5 Ω cm2. Both samples revealed extensive in- and out-diffusion between deposited layers with some consumption ofGaNlayerand formation of TixTa1-xN50 (0<x<25) at the GaN interface. Almost an order of magnitude difference in contact resistances can be attributed to structure and chemical bonding of Ti-O layers formed on the contact surfaces.

Atomie and Electron Structure of Diamond Grain boundaries in a Polycrystalline Film

1997 ◽  
Vol 472 ◽  
Author(s):  
Hideki Ichinose ◽  
Megumi Nakanose ◽  
Yaogan Zhang
Keyword(s):  
Grain Boundaries ◽  
Polycrystalline Diamond ◽  
High Resolution Electron Microscopy ◽  
Electron Structure ◽  
Polished Surface ◽  
Resolution Electron ◽  
Diamond Grain ◽  
Electron Energy Loss ◽  
Π State ◽  
Polycrystalline Diamond Film

AbstractA polycrystalline diamond film was grown on the polished surface of silicon substrate in H2-CO-O2 mixing gas. Atomic and electron structure of grain boundaries in the film was investigated by both high resolution electron microscopy and electron energy loss spectroscopy. CSL boundaries in the film showed characteristic feature in atomic structure; Σ 9 CSL boundary was parallel not to (221) plane but to (114) plane. A new line which correspond to π * state was found in addition to major σ * line in the EELS spectra of the boundary which contained three coordinate atoms. Observed π * line shows occurred change of a dangling bond (pz electron) to π state. No π * line appeared in the EELS spectra obtained from boundaries which contained no three coordinate atom such as (111) Σ 3 boundary.

Atomic and Electronic Structure Analysis of Σ=3, 9 and 27 Boundary, and Multiple Junction in β-SiC

1999 ◽  
Vol 589 ◽  
Author(s):  
K. Tanaka ◽  
M. Kohyama
Keyword(s):  
Electronic Structure ◽  
Energy Loss ◽  
Twin Boundary ◽  
Structural Unit ◽  
High Resolution Electron Microscopy ◽  
Coherent Twin Boundary ◽  
Atomic Structures ◽  
Resolution Electron ◽  
Electron Energy Loss ◽  
Atomic And Electronic Structure

AbstractThe atomic structures of σ=3, 9 and 27 boundaries, and multiple junctions in β-SiC were studied by high-resolution electron microscopy (HREM). Especially, the existence of the variety of structures of σ=3 incoherent twin boundaries and σ=27 boundary was shown by HREM. The structures of σ=3, 9 and 27 boundary were explained by structural unit models. Electron energy-loss spectroscopy (EELS) was used to investigate the electronic structure of grain boundaries. The spectra recorded from bulk, {111}σ=3 coherent twin boundary (CTB) and {1211}σ=3 incoherent twin boundary (ITB) did not show significant differences. Especially, the energy-loss corresponding to carbon 1s-to Φ* transition was not found. It indicates that C atoms exist at grain boundary on the similar condition of bulk

Carbon Onion Films-Molecular Interactions of Multi-Layer Fullerenes

2009 ◽  
Vol 1204 ◽  
Author(s):  
Raed A. Alduhaileb ◽  
Virginia M. Ayres ◽  
Benjamin W. Jacobs ◽  
Xudong Fan ◽  
Kaylee McElroy ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
High Resolution Electron Microscopy ◽  
Synthesis Temperature ◽  
Carbon Onion ◽  
Resolution Electron ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra ◽  
Scanning Electron

AbstractThe evolution of carbon onion structure from spherical to polyhedral is correlated with changes in the sp3/sp2 ratio as a function of increasing synthesis temperature using electron energy loss spectroscopy, scanning electron microscopy, and high resolution electron microscopy. Results that are obtained using asymmetric f-variance versus symmetric Gaussian deconvolution of electron energy loss spectra are compared. The possibility of a separate peak at 287 eV is discussed.

Reactive Multilayers Examined by HRTEM and Plasmon EELS Chemical Mapping

2009 ◽  
Vol 15 (1) ◽  
pp. 54-61 ◽  
Author(s):  
M.A. Mat Yajid ◽  
G. Möbus
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Peak Position ◽  
Multilayer System ◽  
Chemical Mapping ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Before And After ◽  
Relationship Of ◽  
Electron Energy Loss

AbstractWe examine chemical mapping of reaction phases in a Cu-Al multilayer system using low-loss electron energy loss spectroscopy spectrum imaging and image spectroscopy techniques. The sensitivity of the plasmon peak position and shape to various crystal structures and phases is exploited using postprocessing of spectra into second derivative plasmon maps and line scans. Analytical transmission electron microscopy is complemented by studies of the orientation relationship of the multilayer system using high-resolution electron microscopy of interfaces and selected area diffraction. The techniques have been applied to the Cu-Al multilayer sample and sharply bound epitaxial phases are found, before and after heat treatment.

A simple clean vacuum system for carbon-film evaporation

1984 ◽  
Vol 42 ◽  
pp. 630-631
Author(s):  
M.K. Lamvik ◽  
A. LeFurgey
Keyword(s):  
Heavy Atom ◽  
Carbon Film ◽  
High Resolution Electron Microscopy ◽  
Vacuum System ◽  
Heavy Atoms ◽  
Resolution Electron ◽  
Electron Microscopes ◽  
Free Environment ◽  
Vacuum Systems ◽  
Electron Energy Loss

Electron microscopes with clean vacuum systems provide a contaminant-free environment for the specimen, but some of this advantage is lost if the substrate acts as a source of surface-bound contaminants. Particularly for microanalysis of thin specimens, whether by energy-dispersive x-ray spectroscopy or by electron energy-loss spectroscopy, substrates should be free of both organic and inorganic contaminants that might mask elements under Investigation. If specific heavy atom markers are to be studied by high resolution electron microscopy, the substrate should be free of extraneous heavy atoms. The substrate should be as thin and smooth as possible, and it is often helpful that the substrate films be hydrophilic, to assist the binding of some biological particles and improve the spreading of negative stains, when such stains are used.

Nanoscale analysis of a Co-SrTiO3 interface in a Magnetic tunnel junction

2002 ◽  
Vol 746 ◽  
Author(s):  
J.-L. Maurice ◽  
F. Pailloux ◽  
D. Imhoff ◽  
J.-P. Contour ◽  
A. Barthélémy ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Energy Loss ◽  
Electron Energy ◽  
Tunnel Junction ◽  
Electron Energy Loss Spectroscopy ◽  
Magnetic Tunnel Junction ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron ◽  
Electron Energy Loss

ABSTRACTWe use High Resolution Electron Microscopy together with Electron Energy Loss Spectroscopy to analyze the crystallography and the chemical configuration of a Co/SrTiO3 interface in a Co/SrTiO3/La2/3Sr1/3MnO3 magnetic tunnel junction.PACS: 75.47.-m, 75.70.Cn, 68.37.Lp, 79.20.Uv

Electron Microscopy Studies of the High Temperature Oxidation Behavior of NiAl

1996 ◽  
Vol 466 ◽  
Author(s):  
J. C. Yang ◽  
E. Schumann ◽  
I. Levin ◽  
H. Muellejans ◽  
M. Ruhle
Keyword(s):  
Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
High Resolution Electron Microscopy ◽  
Temperature Oxidation ◽  
Lattice Matching ◽  
Transmission Electron ◽  
Resolution Electron ◽  
High Temperature Oxidation Behavior ◽  
Electron Energy Loss

ABSTRACTThe transient oxidation stage of single crystal (001)NiAl was investigated using scanning electron microscopy, transmission electron microscopy, electron diffraction, high resolution electron microscopy and electron energy loss spectroscopy (EELS). (001)NiAl was oxidized in air at 950°C in order to produce transient forms of alumina on the surface. After oxidation, an oxide scale with plate-like surface morphology formed. We found that the main transient alumina polymorph is γ-Al2O3. The platelets which formed on the surface of the oxide are most likely α-A12O3, not θ-Al2O3. Randomly-oriented α-Al2O3 grains were observed at the oxide/metal interface. The NiAl/γ-Al2O3 interfaces were examined with EELS. From the changes observed in the electron energy loss spectra, the interfacial terminating plane is determined. Lattice matching arguments are given to explain why these terminating planes are energetically favorable.

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