Method for the X-ray Diffraction Diagnostics of Crystal Imperfections

2018 ◽  
Vol 12 (2) ◽  
pp. 388-391
Author(s):  
H. R. Drmeyan
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Imperfections

scholarly journals Studies of Crystal Imperfections in Ice with Reference to the Growth Process by the use of X-Ray Diffraction Topography and Divergent Laue Method

1978 ◽  
Vol 21 (85) ◽  
pp. 409-418 ◽  
Author(s):  
Yukiko Mizuno
Keyword(s):  
Dislocation Density ◽  
Growth Process ◽  
Stacking Faults ◽  
Great Majority ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slow Growth Rate ◽  
Crystal Imperfections ◽  
Perfect Dislocation ◽  
Laue Method

AbstractThis paper presents studies on crystal imperfections including basal and non-basal dislocations, small-angle grain boundaries, stacking faults, and dislocation networks in ice using both X-ray diffraction and Laue techniques; these studies examined the growth process or origin of the ice, i.e. ice from glaciers, ice grown from the melt, or ice formed by sublimation. Several hoar crystals were found to be perfect, dislocation-free crystals, this may be due to their very slow growth rate. Dislocations and Shockley-type stacking faults were observed in some crystals. Dislocation density of a hoar crystal is very large at the point at which it started to grow, but away from this region the density becomes so small that no dislocation can be seen. The arrangement and structure of dislocations around vapour figures were also studied by means of X-ray diffraction topography. It was found that the dislocation density is high along the periphery of the vapour hexagon and that the great majority of dislocations within the hexagon are running from its centre towards the vertices or sides of the hexagon. Long screw dislocations with Burgers vector c <0001> were observed in a tabular ice which was formed artificially at a very slight degree of supercooling. The behaviour of dislocations in ice subjected to a tensile stress was studied by the use of the divergent X-ray technique which gives both enlarged Laue spots and a transmission pattern in the same photograph.

Study of X-ray diffraction pictures of crystal imperfections by means of a triple interferometer

1990 ◽  
Vol 118 (1) ◽  
pp. 21-27 ◽  
Author(s):  
A. O. Aboyan ◽  
P. A. Bezirganyan ◽  
A. A. Khzardzhyan
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Imperfections

Grazing Incidence X-Ray Reflectometry Studies of Cadmium Arachidate Langmuir-Blodgett Films

1991 ◽  
Vol 237 ◽  
Author(s):  
B. K. Tanner ◽  
D. K Bowen ◽  
M. C Petty ◽  
S. Swaminathan ◽  
F. Granfeld
Keyword(s):  
Molecular Layer ◽  
Grazing Incidence ◽  
Interface Roughness ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
X Ray ◽  
Langmuir Blodgett ◽  
Crystal Imperfections ◽  
Langmuir Blodgett Films ◽  
Good Agreement

ABSTRACTGrazing incidence X-ray reflectometry has been used to characterize Langmuir-Blodgett films of cadmium arachidate deposited on silicon substrates. The agreement between layer parameters deduced from the interference fringe period and low angle Bragg peak positions was excellent. Good agreement was found between experimental and simulated reflectivity profiles only when interface roughness and a varying molecular layer thickness was included. Inclusion of interface roughness alone results in a substantial enhancement in the intensity of the Bragg peaks. This effect is identified as being equivalent to the reduction in extinction found in classical X-ray diffraction due to crystal imperfections.

X-Ray Studies of Synthetic Radiation-Counting Diamonds

1993 ◽  
Vol 302 ◽  
Author(s):  
Andrew Yacoot ◽  
Moreton Moore ◽  
Anthony Makepeace
Keyword(s):  
Electric Field ◽  
Nitrogen Content ◽  
Medical Applications ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Imperfections ◽  
Synthetic Diamonds ◽  
Counting Mode

ABSTRACTSynthetic diamonds with a nitrogen content less than 100ppm may be used as radiation dosimeters in a conduction counting mode, and are especially useful in medical applications. Crystal imperfections, revealed by X-ray diffraction topography, were found to affect counting performance. The best quality diamond gave the highest photocurrent (500nA at 50 V mm−1 and 2.75 Gy min−l). Diamonds containing dislocations had lower photocurrents but had the advantage of shorter settling times (seconds rather than minutes). Placing contacts on two opposite cube {100} faces gave a higher photocurrent than on a pair of octahedral {111} faces. Higher photocurrents were also achieved when the majority of dislocations were perpendicular rather than parallel to the electric field. Some recommendations for selecting synthetic diamonds for dosimeters are given.

scholarly journals Studies of Crystal Imperfections in Ice with Reference to the Growth Process by the use of X-Ray Diffraction Topography and Divergent Laue Method

1978 ◽  
Vol 21 (85) ◽  
pp. 409-418 ◽  
Author(s):  
Yukiko Mizuno
Keyword(s):  
Dislocation Density ◽  
Growth Process ◽  
Stacking Faults ◽  
Great Majority ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slow Growth Rate ◽  
Crystal Imperfections ◽  
Perfect Dislocation ◽  
Laue Method

Abstract This paper presents studies on crystal imperfections including basal and non-basal dislocations, small-angle grain boundaries, stacking faults, and dislocation networks in ice using both X-ray diffraction and Laue techniques; these studies examined the growth process or origin of the ice, i.e. ice from glaciers, ice grown from the melt, or ice formed by sublimation. Several hoar crystals were found to be perfect, dislocation-free crystals, this may be due to their very slow growth rate. Dislocations and Shockley-type stacking faults were observed in some crystals. Dislocation density of a hoar crystal is very large at the point at which it started to grow, but away from this region the density becomes so small that no dislocation can be seen. The arrangement and structure of dislocations around vapour figures were also studied by means of X-ray diffraction topography. It was found that the dislocation density is high along the periphery of the vapour hexagon and that the great majority of dislocations within the hexagon are running from its centre towards the vertices or sides of the hexagon. Long screw dislocations with Burgers vector c &lt;0001&gt; were observed in a tabular ice which was formed artificially at a very slight degree of supercooling. The behaviour of dislocations in ice subjected to a tensile stress was studied by the use of the divergent X-ray technique which gives both enlarged Laue spots and a transmission pattern in the same photograph.

scholarly journals Crystal Imperfections of Industrial Vanadium Phosphorous Oxide Catalysts

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1325
Author(s):  
Isabella Kappel ◽  
Sebastian Böcklein ◽  
SoHyun Park ◽  
Michael Wharmby ◽  
Gerhard Mestl ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Bragg Reflection ◽  
Oxide Catalysts ◽  
Laboratory Scale ◽  
Vanadyl Pyrophosphate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Imperfections ◽  
Synchrotron Powder Diffraction

This study presents information about crystal imperfections in the main phase of industrial vanadium phosphorous oxide catalysts that are used to catalyze the oxidation of n-butane to maleic anhydride, being an important intermediate in the chemical industry. The mechanism of this reaction is still debated, and the catalytically active and selective surface centers have not yet been identified. The results presented are based on X-ray diffraction data obtained by both laboratory-scale and synchrotron powder diffraction experiments, as well as laboratory-scale single-crystal diffraction experiments. It has been proven that pronounced Bragg reflection broadening effects found in laboratory-scale powder diffraction patterns of industrial VPO catalysts are real and not due to an insufficient 2-θ resolution of the apparatus. In the framework of this work, a powder diffraction full profile fitting strategy was developed using the TOPAS software, which was applied to analyze the X-ray diffraction data of four differently activated industrial catalyst samples, originating from one batch after they had been catalytically tested. It was found that the reflection broadening is mainly caused by an anisotropic crystal size, which results in platelet-shaped crystallites of vanadyl pyrophosphate. A further contribution to the reflex broadening, especially for (111), was found to be a result of stacking faults perpendicular to the a direction in the crystal structure of vanadyl pyrophosphate. These results were used to elaborate on possible correlations between structural proxies and catalytic performance. A direct correlation between the extension of coherently scattering domains in the z direction and the catalyst’s selectivity could be proven, whereas the activity turned out to be dependent on the crystallite shape. Regarding the phase contents, it could be shown that sample catalysts containing a higher amount of β-VO(PO3)2 showed increased catalytic activity.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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