Low Temperature - High Pressure Oxidation of 3C-SiC

1994 ◽  
Vol 357 ◽  
Author(s):  
Christine Caragianis-Broadbridge ◽  
Barbara L. Walden ◽  
Juliana Blaser ◽  
Cleva Ow Yang ◽  
David C. Paine
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Pressure Oxidation ◽  
Planar Defects ◽  
Transmission Electron ◽  
Before And After ◽  
Crystal Films ◽  
Film Microstructure

AbstractSingle crystal films of n-type 3C-SiC were hydrothermally processed at pressures ranging from 10 to 70 MPa at 550°C. To study the effects of initial thin film microstructure on hydrothermal processing, two different samples of CVD-grown SiC were studied: one, 200 nm thick, contained low angle boundaries and a high density of planar defects; the other, 3500 nm thick, was planar and contained relatively few defects. Raman Spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to study the chemistry and microstructure of the SiC material both before and after hydrothermal treatment. This study reveals that low temperature (T=550°C) oxidation of single crystal epitaxial SiC is possible but that the resulting oxide film microstructure is strongly dependent on the initial film microstructure and oxidation is greatly enhanced along low angle grain boundaries and on planar defects.

Evaporated Titanium Films on Rocksalt

1967 ◽  
Vol 25 ◽  
pp. 296-297
Author(s):  
Frank E. Wawner ◽  
Kenneth R. Lawless
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Single Crystal ◽  
High Purity ◽  
Early Stages ◽  
Transmission Electron ◽  
Single Crystal Films ◽  
Crystal Films ◽  
Purity Titanium

Thin single crystal films of high purity titanium were needed in our laboratory for investigations of the early stages of the oxidation of titanium. Experiments were carried out to determine the feasibility of preparing single crystal titanium films of different orientations by evaporation onto the (100), (110) and (111) surfaces of rocksalt. The structures of these films were investigated by transmission electron microscopy and electron diffraction.

Surface Alteration of Nd-Bearing Zirconolite Following Hydrothermal Treatment

2000 ◽  
Vol 663 ◽  
Author(s):  
Zhaoming Zhang ◽  
Eric R. Vance ◽  
Mark G. Blackford
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Treatment ◽  
Photoelectron Spectroscopy ◽  
Deionized Water ◽  
X Ray ◽  
Transmission Electron ◽  
Dissolution Tests ◽  
Before And After ◽  
Surface Alteration ◽  
Durability Testing

ABSTRACTStatic dissolution tests on Nd-bearing zirconolite were conducted in deionized water at 150°C for up to 6 months. Surfaces, both before and after aqueous dissolutions, were examined using X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). Individual submicron-sized crystals wereobserved only on some zirconolite grains after hydrothermal treatment for one week, and were identified as brookite (possibly plus anatase) by Transmission Electron Microscopy (TEM). The number of secondary crystals present on the zirconolite surface was, however, reduced significantly after 6 months of durability testing. The results of electron microscopy studies are consistent with those obtained from XPS in that the average Ca and Ti concentrations of the top surface layer (< 5 nm) decreased slightly with respect to Zr, while the average Al concentration increased after durability testing.

scholarly journals Synthesis of Chromium Carbide Nanopowders by Microwave Heating and Their Composition and Microstructure Change under Gamma Ray Irradiation

Molecules ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 16 ◽  
Author(s):  
Kai Jin ◽  
Yuanbo Jia ◽  
Zhiwei Zhao ◽  
Weiqiang Song ◽  
Shun Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Microwave Heating ◽  
Chromium Carbide ◽  
Photoelectron Spectroscopy ◽  
Gamma Ray ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After ◽  
Gamma Ray Irradiation

Chromium carbide nanopowders were synthesized by mechanical alloying-assisted microwave heating. The effect of gamma irradiation on phase composition and microstructure of chromium carbide nanopowders synthesized by the microwave heating method was analyzed. The samples were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The results showed that well-dispersed chromium carbide nanopowders can be synthesized by maintaining the temperature at 1000 °C for 1 h. Gamma ray irradiation had an important effect on the microstructure of chromium carbide nanopowders. The interplanar spacings of chromium carbide (110) crystal faces before and after gamma ray irradiation were 0.3725 nm and 0.3824 nm, respectively. The crystal structure of chromium carbide was changed by gamma ray irradiation. Gamma ray irradiation can also increase the binding energy of chromium carbide, which is beneficial to improve the thermal stability and mechanical properties of chromium carbide at high temperature.

Growth of Rock-Salt and Spinel Structured Oxides on α-Al2O3, c-ZrO2 and MgO

1994 ◽  
Vol 343 ◽  
Author(s):  
Sundar Ramamurthy ◽  
Paul G. Kotula ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Single Crystal ◽  
Rock Salt ◽  
Low Voltage ◽  
Orientation Relationships ◽  
Plan View ◽  
Transmission Electron ◽  
Crystal Films ◽  
Α Al2o3

ABSTRACTPulsed-laser deposition has been used to grow thin films of the rock-salt and spinel structured oxides NiO, CoO and C03O4 on single-crystal substrates of α-Al2O3, MgO and C-Z1O2. The resultant microstructures were characterized in plan-view by transmission electron microscopy and by low-voltage scanning electron microscopy. In all the depositions, the parameters could be controlled to grow predominantly single-crystal films. In the NiO/(0001)α-Al2O3 and CoO/(100)c-ZrO2 systems, {111}-oriented films were observed which were found to be twinned close to 60° and 90° about <111> respectively. Growth of cobalt oxide films on (100) MgO at 800°C and 15 mTorr of oxygen produced {100}-oriented domains of C03O4 meeting at antiphase boundaries. These observations and other recent studies re-emphasize the role of substrate crystallography in governing the orientation relationships in the overlayer.

Evaporated Copper Deposits on Nickel Substrates

1967 ◽  
Vol 25 ◽  
pp. 298-299
Author(s):  
William L. Goodman ◽  
Kenneth R. Lawless
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystal ◽  
High Purity ◽  
Room Temperature ◽  
Copper Deposits ◽  
Transmission Electron ◽  
Crystal Films ◽  
Nickel Substrates ◽  
Thin Wedge

The structure of thin copper electrodeposits on single crystal nickel substrates has been previously studied in this laboratory. We thought it would be desirable to prepare similar bi-crystal films by the evaporation of copper onto nickel so that a comparison of the structures obtained by the two methods of deposition could be made. For this purpose, single crystal nickel films of (100), (110) and (111) orientations were prepared by evaporation onto heated (410°C) rocksalt substrates. Without breaking the vacuum, copper was evaporated in the form of a thin wedge onto the nickel surfaces after the nickel was cooled to room temperature. High purity (99.999%) metals were used, and these were thoroughly outgassed before evaporation. The thickness gradient of copper was obtained by moving a shutter between the substrate and the copper source during the evaporation. The resulting bi-crystal films were then stripped from the rocksalt and examined by transmission electron microscopy.

A Fundamental Study on the Chemical Stability of La1−xSrxCo0.2Fe0.8O3−δ Cathodes for Intermediate Temperature Solid Oxide Fuel Cells

2017 ◽  
Vol 14 (3) ◽  
Author(s):  
Yufeng Qiu ◽  
Jian Pu ◽  
Jian Li ◽  
Yihui Liu ◽  
Bin Hua
Keyword(s):  
Electron Microscopy ◽  
Chemical Stability ◽  
Photoelectron Spectroscopy ◽  
Surface Segregation ◽  
Treatment Time ◽  
Driving Forces ◽  
Secondary Phase ◽  
Fundamental Study ◽  
Transmission Electron ◽  
Before And After

The chemical stability of La1−xSrxCo0.2Fe0.8O3−δ (x = 0, 0.4, 0.6, and 1) oxides before and after annealing at 750 °C in air is investigated by field emission scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and environmental transmission electron microscopy (TEM). Results indicate that Sr surface segregation has initially occurred at the sintering stage, and then, the secondary-phase particles are formed with increasing the heat-treatment time at 750 °C in air. Increasing Sr content accelerates Sr segregation on the surface, because of two driving forces including interaction forces in the crystal lattice and thermal activation. AES and XPS results reveal that Sr and Co segregations toward the surface have great contributions to the chemical instability of La1−xSrxCo1−yFeyO3−δ (LSCF) during annealing.

scholarly journals Nano-scale characterisation of sheared β” precipitates in a deformed Al-Mg-Si alloy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Emil Christiansen ◽  
Calin Daniel Marioara ◽  
Bjørn Holmedal ◽  
Odd Sture Hopperstad ◽  
Randi Holmestad
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scale Structure ◽  
Planar Defects ◽  
Nano Scale ◽  
Transmission Electron ◽  
Before And After ◽  
Peak Aged ◽  
Microscopy Techniques

AbstractThis paper compares the nano-scale structure of β” precipitates in a peak-aged Al-Mg-Si alloy before and after deformation. Three complementary advanced transmission electron microscopy techniques are used to reveal the structures and elucidate the interaction between dislocations and β” precipitates. We show that the needle-like and semi-coherent β” precipitates are sheared several times on different planes by dislocations during deformation, with no indications that they are bypassed or looped. Our results show that dislocations cut through precipitates and leave behind planar defects lying on planes inclined to 〈100〉 directions inside the precipitates. The results also indicate that precipitates are sheared in single steps, and the implication of this observation is discussed in terms of slip behaviour.

Characterization of BN Rich Layer on Ammonia Treated Nextel™312 Fibers

1994 ◽  
Vol 365 ◽  
Author(s):  
N.R. Khasgiwale ◽  
E.P. Butler ◽  
L. Tsakalakos ◽  
D.A. Hensley ◽  
W.R. Cannon ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Layer Thickness ◽  
Photoelectron Spectroscopy ◽  
Fiber Surface ◽  
Ammonia Treatment ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After ◽  
High Resolution Tem

ABSTRACTA BN rich layer grown on Nextel™312 fibers by appropriate ammonia treatments was evaluated using various complimentary techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM)/ Parallel Electron Energy Loss Spectroscopy (PEELS in TEM). Three different ammonia treatments were studied. Ammonia treatment resulted in crystallization of the Nextel™312 fiber. The BN rich surface layer formed due to ammonia treatment was clearly detected in XPS and PEELS both before and after oxidation. The layer thickness was estimated to be between 5–10 nm. The layer was stable after oxidation treatment at 600°C for 100 hours. High resolution TEM observations of the fiber surface revealed a variable BN rich layer thickness. Patches of turbostratic BN were observed under certain conditions, however mostly the layer appeared to be amorphous.

Formation of Single Crystal Nanowires of GaN on the Si Substrates

2005 ◽  
Vol 475-479 ◽  
pp. 4175-4178 ◽  
Author(s):  
Cheng Shan Xue ◽  
Zhi Hua Dong ◽  
Hui Zhao Zhuang ◽  
Haiyong Gao ◽  
Yi'an Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Si Substrates ◽  
Transmission Electron ◽  
Scanning Electron ◽  
Sputtering System

An extreme thin SiC buffer and Ga2O3 layer were deposited on silicon substrate sequentially with a r.f. magnetron sputtering system. Then the sample was annealed in the ambiance of ammonia at high temperature. Nanowires were found when the sample was tested with scanning electron microscopy (SEM). The composition of the nanowires is found to be GaN when the sample was tested with X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). A nanowire was observed with transmission electron microscopy and it was even and uniform, with diameter of about 60nm. And the nanowire can be testified of wurtzite single crystal structure by electron diffraction (ED) analysis attached to the TEM. The high-resolution transmission electron microscopy (HRTEM) analysis to the nanowire indicates that the nanowire was single crystal with very good quality.

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