Investigation of Subcontact Layers in SiC after Diffusion Welding

2008 ◽  
Vol 600-603 ◽  
pp. 647-650 ◽  
Author(s):  
Oleg Korolkov ◽  
Natalja Sleptsuk ◽  
Alla A. Sitnikova ◽  
Mart Viljus ◽  
Toomas Rang
Keyword(s):  
Silicon Carbide ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Amorphous Layer ◽  
Interface Layer ◽  
Dark Field ◽  
Diffusion Welding ◽  
Transmission Electron ◽  
First Results ◽  
Diffraction Picture

In our early analytic reports [1,2] has been made the supposition that during the diffusion welding (DW) in subcontact area of SiC is formed the intermediate amorphous layer. In the present work are given the first results of transmission electron microscopy (TEM) and electron diffraction investigations of subcontact layers in n0-n- 4H-SiC. TEM examinations show that the boundary between aluminium and silicon carbide looks like stripy interface layer of ~ 25 nm thickness. This is the evidence that during diffusion welding in subcontact surface layer of SiC the shear micro deformations have been taking place and due to this process the plane inclusions of small-grained phase have been appeared. The image of contact area obtained in diffracted SiC rays (dark field) apparently confirms that stripy zone belongs to silicon carbide because the aluminium (black zone) fell out of contrast. Diffraction picture obtained from bulk zone of silicon carbide looks like monocrystallin, but the micro diffraction pattern obtained from the subcontact (stripy zone) gives a lot of concentric rings, that makes evidential the fact of existence of small-grained inclusions. Deciphering of this electron-diffraction pattern reveals the presence of such elements as residue SiC, Al, Si, as well as inclusions of graphite.

Microstructure evolution of Ca0.33CoO2 thin films investigated by high-angle annular dark-field scanning transmissionelectron microscopy

2009 ◽  
Vol 24 (1) ◽  
pp. 279-287 ◽  
Author(s):  
Rong Huang ◽  
Teruyasu Mizoguchi ◽  
Kenji Sugiura ◽  
Shin-ichi Nakagawa ◽  
Hiromichi Ohta ◽  
...  
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Solid Phase ◽  
Spherical Aberration ◽  
Amorphous Layer ◽  
Dark Field ◽  
High Angle ◽  
Orientation Relationships ◽  
Transmission Electron ◽  
Annular Dark Field

Microstructures of epitaxial Ca0.33CoO2 thin films, which were grown on m plane and c(0001) plane of α–Al2O3 by the reactive solid-phase epitaxy (R-SPE) method and the subsequent ion-exchange treatment, were investigated in detail by using selected-area electron diffraction, high-resolution transmission electron microcopy, spherical-aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (Cs-corrected HAADF-STEM), and electron energy-loss spectroscopy (EELS). Detailed electron diffraction analyses reveal that the orientation relationships between Ca0.33CoO2 thin film and substrate are and , having an angle of about 43° with for the film deposited on m plane, and and for the film deposited on c(0001) plane though a Ca–Al–O amorphous layer formed between them. CoO seed layer near the interface and residual Co3O4 phase inside the films were observed and identified by HAADF-STEM and EELS in both samples. Such microstructural configuration indicates that the processes of film growth during R-SPE are (i) oxidation of CoO into Co3O4 with residual CoO layer near the interface and (ii) intercalation of Na+ layer into Co3O4 to achieve the layered NaxCoO2 film while forming Na–Al–O amorphous layer at the interface.

In-Situ Transmission Electron Microscopy Investigation of Aluminum Induced Crystallization of Amorphous Silicon

2008 ◽  
Vol 1066 ◽  
Author(s):  
Ram Kishore ◽  
Renu Sharma ◽  
Satoshi Hata ◽  
Noriyuki Kuwano ◽  
Yoshitsuga Tomokiyo ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Amorphous Silicon ◽  
Diffraction Pattern ◽  
Electron Diffraction Pattern ◽  
Polycrystalline Silicon ◽  
Nanocrystalline Silicon ◽  
Transmission Electron ◽  
In Situ Heating ◽  
Induced Crystallization

ABSTRACTThe interaction of amorphous silicon and aluminum films to achieve polycrystalline silicon has been investigated using transmission electron microscope equipped with in-situ heating holder. Carbon coated nickel grids were used for TEM studies. An ultra high vacuum cluster tool was used for the deposition of a ∼50nm a-Si films and a vacuum deposition system was used to deposit a ∼50nm Al films on a-Si film. The microstructural features and electron diffraction in the plain view mode were observed with increase in temperature starting from room temperature to 275 °C. The specimen was loaded inside TEM heating holder. The temperature was measured and kept constant for 5 minutes during which the microstructure at fixed magnification of X63K was recorded and the electron diffraction pattern of the same area was also recorded. The temperature was then increase and fixed at desired value and microstructure and EDP were again recorded. The temperatures used in this experiment were 30, 100, 150, 200, 225, 275°C. A sequential change in microstructural features and electron diffraction pattern due to interfacial diffusion of boundary between Al and amorphous Si was investigated. Evolution of polycrystalline silicon with randomly oriented grains as a result of a-Si and Al interaction was revealed. After the in-situ heating experiment the specimen was subjected to high resolution TEM and EDS investigations after removing the excess Al. The EDS analysis of the crystallized specimen was performed to locate the Al distribution in the crystallized silicon. These studies show that the Al induced crystallization process can be used to prepare polycrystalline as well as nanocrystalline silicon by controlling the in-situ annealing parameters. The investigations are very useful as the nanocrystalline silicon is being investigated for its use in developing high efficiency silicon solar structures.

Analysis of Reflection High Energy Electron Diffraction Pattern of Silicon Carbide Grown on Silicon

1995 ◽  
Vol 399 ◽  
Author(s):  
G. Teichert ◽  
J. Pezoldt ◽  
V. Cimalla ◽  
O. Nennewitz ◽  
L. Spiess
Keyword(s):  
Silicon Carbide ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Process Parameters ◽  
Electron Diffraction Pattern ◽  
Lattice Relaxation ◽  
High Energy ◽  
Morphology Evolution ◽  
Rheed Pattern ◽  
High Energy Electron

ABSTRACTRHEED pattern of SiC layers on both (100) and (111)Si grown by carbonization were studied. Different deviations from the single crystalline structure were found ranging from twinning up to changes in the orientation and textured growth. Special attention was drawn on lattice relaxation and morphology evolution during the growth of the formed SiC. Relationships between the occurrence of typical RHEED pattern and the morphology and process parameters are presented.

Polytypoids in high Tc thallium based superconducting materials

1990 ◽  
Vol 5 (8) ◽  
pp. 1620-1624
Author(s):  
A. K. Singh ◽  
M. A. Imam ◽  
K. Sadananda ◽  
S. B. Qadri ◽  
E. F. Skelton ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Electron Diffraction Pattern ◽  
Stacking Faults ◽  
Superconducting Materials ◽  
Superconducting Properties ◽  
High Tc ◽  
Transmission Electron

Several high Tc compounds containing Tl (thallium) were prepared starting from different initial compositions. Superconducting properties and the structure were determined for each sample. Electron diffraction and transmission electron microscopy showed the existence of polytypic high Tc compounds with the same a- and b-axes but different c-axis values. The c-axis appears to increase approximately in integral multiples of 0.15 nm with varying composition and is associated with the insertion of Cu–Ca or Cu–Tl layers in each unit cell. Several random stacking faults were also noted, which give rise to diffuse streaking in the electron diffraction pattern.

The Initial Stages of Oxide Film Formation on Copper and Some Copper Alloys

CORROSION ◽  
1969 ◽  
Vol 25 (7) ◽  
pp. 291-299 ◽  
Author(s):  
M. D. SANDERSON ◽  
J. C. SCULLY
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Film Formation ◽  
Copper Alloys ◽  
Amorphous Layer ◽  
Oxide Formation ◽  
Thin Foils ◽  
Transmission Electron ◽  
Crystallographic Planes

Abstract The initial stages of oxide formation on thin foils of copper, Cu-2.5Al-2.5Si, and Cu-7.5Al-2Si alloys in moist atmospheres of oxygen and sulfur dioxide have been studied by transmission electron microscopy and electron diffraction over the temperature range 200-380 C (392-716 F). On the Cu-2.5Al-2.5Si alloy grain boundaries and twin boundaries are preferential sites for oxide nucleation. On the Cu-7.5Al-2Si alloy no preferential sites are observed. The relative reactivities of different crystallographic planes are the same for the alloys as for the metal. On oxidized thin foils a prenucleation thermal pitting phenomenon has been observed at temperatures very much lower than the thermal pitting observed by other workers. Oxide nuclei have been observed to form on a thin amorphous layer of oxide even when there is no metal directly underneath. These results are discussed with reference to current theories on the initial stages of oxide formation. It is concluded that in the prenucleation stage the metal surface is covered with a highly mobile layer of cations and anions.

Electron microscopic investigation of the structure and morphology of syndiotactic polypropylene

1989 ◽  
Vol 47 ◽  
pp. 358-359
Author(s):  
Andrew J. Lovinger ◽  
Bernard Lotz ◽  
Don D. Davis
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Dark Field ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Dilute Solution ◽  
Electron Microscopic ◽  
Syndiotactic Polypropylene ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron

In contrast to its isotactic isomer, syndiotactic polypropylene has received only little attention. Our main source of understanding of its structure is the X-ray study by Conradini et al., who found the chains to have a (t2g2)2 conformation (corresponding to a 4∗2/1 helix with molecular repeat 0.74 nm), and to be packed in a C-centered unit cell as shown in the left side of Fig. 1. We have recently begun a study of the structure, crystallization, and morphology of syndiotactic polypropylene using electron microscopy and diffraction. Here we concentrate specifically on the electron-diffraction evidence as a function of temperature, in order to obtain an understanding of the evolution and variation of structure in this polymer.Thin films of syndiotactic polypropylene (synthesized by Dr. R. E. Cais as reported previously) were prepared by casting from dilute solution in xylenes at ca. 140°c onto freshly cleaved mica substrates. Following evaporation of the solvent, they were melted and then isothermally crystallized at a variety of temperatures. After shadowing with Pt/C and coating with carbon, they were floated off their substrates for examination by transmission electron microscopy (bright- and dark-field) and selected-area electron diffraction at 100-200 keV.

scholarly journals Application of scanning electron diffraction in the transmission electron microscope for the characterisation of dislocations in minerals

2018 ◽  
Vol 83 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Billy C. Nzogang ◽  
Alexandre Mussi ◽  
Patrick Cordier
Keyword(s):  
Electron Diffraction ◽  
Dark Field ◽  
Perfect Crystal ◽  
Crystal Defects ◽  
Fine Tuning ◽  
Acquisition Time ◽  
Short Acquisition Time ◽  
Transmission Electron ◽  
Probe Location ◽  
Scanning Electron

AbstractWe present an application of scanning electron diffraction for the characterisation of crystal defects in olivine, quartz and phase A (a high pressure hydrated phase). In this mode, which takes advantage of the ASTAR™ module from NanoMEGAS, a slightly convergent probe is scanned over the sample with a short acquisition time (a few tens of ms) and the spot patterns are acquired and stored for further post-processing. Originally, orientation maps were constructed from automatic indexing at each probe location. Here we present another application where images are reconstructed from the intensity of diffraction spots, producing either so-called ‘virtual’ bright- or dark-field images. We show that these images present all the characteristics of contrast (perfect crystal or defects) of conventional transmission electron microscopy images. Data are acquired with a very short time per probe location (a few tens of milliseconds), this technique appears very attractive for the characterisation of beam-sensitive materials. However, as the acquisition is done at a given orientation, fine tuning of the diffraction conditions at a given location for each reflection is not possible. This might present a difficulty for some precise, quantitative contrast analysis.

scholarly journals Approach to observe folded chains of syndiotactic polystyrene on solution-grown crystals by atomic force microscopy

e-Polymers ◽  
2003 ◽  
Vol 3 (1) ◽  
Author(s):  
Nobuyuki Suto ◽  
Atsuhiro Fujimori ◽  
Toru Masuko
Keyword(s):  
Atomic Force Microscopy ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Electron Diffraction Pattern ◽  
Polymer Chains ◽  
Syndiotactic Polystyrene ◽  
Mesoscopic Scale ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

Abstract Folded chains of syndiotactic polystyrene located on the surface of its solution-grown crystals (SGCs) have been observed on nano scale by use of atomic force microscopy (AFM). Transmission electron micrographs of the SGCs on the mesoscopic scale exhibited truncated-lozenge platelets accompanied by a sharp electron diffraction pattern of the β”-form. AFM images of selected areas on the SGC surface indicated folded chains existing periodically on the surface with c. 1.3 to 1.4 nm spacing, suggesting that the polymer chains are aligned in parallel with the {230} growth faces of SGC.

The Art and Application of Large Angle Convergent Beam Electron Diffraction

2012 ◽  
Vol 186 ◽  
pp. 16-19 ◽  
Author(s):  
Elżbieta Jezierska
Keyword(s):  
Electron Diffraction ◽  
Large Angle ◽  
Antiphase Boundary ◽  
Antiphase Domain ◽  
Dark Field ◽  
Convergent Beam Electron Diffraction ◽  
Intermetallic Alloys ◽  
Beam Electron ◽  
Transmission Electron ◽  
Convergent Beam

The antiphase domain structure in Ni3Al and Al3Ti+Cu intermetallic alloys was recognized by conventional transmission electron microscopy and large angle convergent beam electron diffraction methods. In the case of antiphase boundary the superlattice excess line is split into two lines with equal intensity on bright and dark field LACBED pattern. This splitting can be considered as typical and used to identify APBs. The recognition between perfect structure of the defect-free matrix and the screw deviation around the nanopipes in GaN epilayers was performed with high accuracy using Zone Axis LACBED images.

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