Imaging and Characterization of Crystal Defects

2016 ◽  
pp. 501-552
Author(s):  
Jian Min Zuo ◽  
John C. H. Spence
Keyword(s):  
Crystal Defects

Electron microscopy and krypton adsorption characterization of high-purity MgO powder

1986 ◽  
Vol 1 (1) ◽  
pp. 114-119
Author(s):  
M. Bretz ◽  
A. G. Shastri ◽  
J. Schwank
Keyword(s):  
Large Scale ◽  
Gas Adsorption ◽  
Crystal Surface ◽  
Crystal Defects ◽  
Atomic Scale ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Krypton Adsorption

A promising method for the preparation of sizeable quantities of structurally well-defined, highpurity MgO powder is reported. The morphology and surface uniformity of the powder is comparable to that of MgO smokes but with narrow size distribution of particles. Sample characterization of these oxide powders is accomplished by combining structural TEM/STEM examination with krypton gas adsorption isotherms. The latter technique is sensitive to the presence of surface hydroxyl groups and of surface roughness on an atomic scale. Highresolution TEM indicates a perfect cubic morphology, intra-crystallite orientation, and dendritic sintering of cubes. In the STEM mode sharp convergent beam electron diffraction patterns are obtained, and in thick specimen regions Kikuchi lines appear, indicating the absence of crystal defects. After prolonged outgassing to remove surface hydroxyl groups, a krypton adsorption isotherm contains a near vertical submonolayer riser and second layer step along with partial wetting features near saturation. These near-ideal dendritic ceramic powders, therefore, provide a research bridge between single crystal surface studies and large-scale powder technology.

Cross-Sectional TEM Characterization of Re-Based Diffusion Barrier on Nb Substrate

2011 ◽  
Vol 696 ◽  
pp. 318-323
Author(s):  
S. Eni ◽  
Y. Wang ◽  
N. Hashimoto ◽  
Somei Ohnuki ◽  
Toshio Narita
Keyword(s):  
Diffusion Barrier ◽  
Stacking Faults ◽  
Crystal Defects ◽  
Coating Process ◽  
Cross Sectional ◽  
Tem Characterization ◽  
Barrier Coating ◽  
Bcc Structure ◽  
Coated Layer

Cross-sectional structures of a Re-based diffusion barrier coating on Nb as ultra high temperature material were investigated in order to verify the crystalline structure and composition of the coated layer. Three types coating specimens were prepared by electroplating Re from an aqueous solution on an Nb substrate, followed by Cr-pack cementation in vacuum. The coating process produced three distinct layers; an outer Cr(Re) layer, an intermediate Re-Cr-Nb layer, and an inner Nb(Re) layer. A crystal structure of Cr(Re) and Nb(Re) layers possess similar single crystal bcc structure. The Re-Cr-Nb layer expected to act as a diffusion barrier between the substrate and the outer reservoir layer was comprised of cubic c phase and hexagonal Laves C14 phase. Moreover, several crystal defects such as dislocations and stacking faults as well as voids and cracks are observed in the coating specimen.

Characterization of Defects and Interfaces by the Ion Channeling Technique

1984 ◽  
Vol 41 ◽  
Author(s):  
W. K. Chu ◽  
S. T. Picraux
Keyword(s):  
Ion Beam ◽  
Strain Analysis ◽  
Crystal Defects ◽  
Interfacial Structure ◽  
Heteroepitaxial Growth ◽  
Ion Channeling ◽  
Light Ions ◽  
Recent Developments ◽  
Fast Light

AbstractChanneling of fast, light ions in crystals has been widely used as a tool for studying crystal defects. This subject has been reviewed earlier at MRS-1980. During MRS-1980, principles of ion channeling, and examples of channeling analysis on bulk defects and surface structures, lattice location of impurities, and clustering phenomena were given. In this review, we give a brief overview of defect studies by the channeling technique and then elaborate on recent developments in channeling analysis of interfacial structure. The ion beam channeling technique permits characterization of heteroepitaxial growth starting at monolayer coverages and allows quantitative measurement of the lattice strain in heteroepitaxial layers. The strain analysis has been developed for multilayer structures and, for example, the tetragonal distortions of strained-layer superlattices can be determined for lattice mismatches as low as 0.2% corresponding to lattice distortions of 0.01Å.

scholarly journals Irradiation Hardening and Microstructure Characterization of Zr -1% Nb During Low Dose Neutron Irradiation

2021 ◽  
Vol 10 (2) ◽  
pp. 63-72
Author(s):  
Carolina Vazquez ◽  
Eugenia Zelaya ◽  
Ana Maria Fortis ◽  
Patricia B. Bozzano
Keyword(s):  
Neutron Irradiation ◽  
Low Dose ◽  
Zirconium Alloys ◽  
Life Time ◽  
Tensile Tests ◽  
Crystal Defects ◽  
Second Phase ◽  
Hydrogen Damage ◽  
Transmission Electron

Due to low neutron absorption cross section, high mechanical strength, high thermal conductivity and good corrosion resistance in water and steam, Zirconium alloys are widely used as fuel cladding material in nuclear reactors. During life-time of a reactor the microstructure of this alloy is affected due to, among other factors, radiation damage and hydrogen damage. In this work mechanical properties changes on neutron irradiated Zr-1wt.% Nb at low temperatures (< 100 °C) and low dose (3.5 ´ 1023 n m-2 (E > 1 MeV)) were correlated with hydrides and crystal defects evolution during irradiation. To achieve this propose, tensile tests of: 1) Non-hydrided and non-irradiated material, 2) Hydrided and non-irradiated material and 3) Hydrided and irradiated material were performed at 25 ºC and 300 ºC. Different phases, hydrides and second phase precipitates were characterized by transmission electron microscopy (TEM) techniques. For the hydrided and irradiated material, the ductility decreased sharply with respect to the hydrided and non-irradiated material, among other factors, due to the change in the microstructure produced mainly by neutron irradiation. Even if the presence of the hydride ζ (zeta) was observed, both in the irradiated and non-irradiated material, tensile tests showed that ζ-hydrides did not affect ductility, since hydrided samples are more ductile than non-hydrided samples.

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