scholarly journals X-ray diffraction from f.c.c. crystals containing a non-random distribution of deformation faults

1981 ◽  
Vol 37 (a1) ◽  
pp. C272-C272
Author(s):  
S. Lele ◽  
D. Pandey
Keyword(s):  
Random Distribution ◽  
X Ray Diffraction ◽  
X Ray

Synthesis and Characterization of Cu2FeSnS4 Semiconductor Nanocrystals with Zincblende Structure

2012 ◽  
Vol 512-515 ◽  
pp. 2019-2022 ◽  
Author(s):  
Xiao Lu Liang ◽  
Xian Hua Wei
Keyword(s):  
Random Distribution ◽  
Semiconductor Nanocrystals ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Nir Absorption ◽  
Average Size

Cu2FeSnS4semiconductor nanocrystals with zincblende structure have been successfully synthesized by a hot-injection approach. Cu+, Fe2+, and Sn4+cations have a random distribution in the zincblende unit cell, and the occupancy possibilities are 1/2, 1/4 and 1/4, respectively. Those nanocrystals were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive spectroscopy (EDS), and UV-Vis-NIR absorption spectroscopy. The Cu2FeSnS4 nanocrystals have an average size of 7.5 nm and a band gap of 0.92 eV.

Direct X-Ray Measurement of Residual Strains in Textured Steel

1983 ◽  
Vol 27 ◽  
pp. 197-206
Author(s):  
C. P. Gazzara
Keyword(s):  
Residual Stress ◽  
Crystal Lattice ◽  
Elastic Constants ◽  
Random Distribution ◽  
Elastic Anisotropy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Residual Strains ◽  
Residual Stress Analysis ◽  
Textured Materials

One of the most detrimental effects on the accuracy of an X-ray diffraction residual stress analysis, XRDRSA(l), is found in the examination of textured materials. The degree of elastic anisotropy and texture is in general agreement with the extent of the error in the residual stress. Several approaches have been made to correct for the effects of texture, particularly involving experimental techniques. Reviews of such efforts are given by H. D811e(2), v.M. Hauk﹛3) and G. Maeder, J.L. Lebrun and J.M. Sprauel (4), just to mention a few.A brief chronology of the texture corrections involved in XRDRSA follows. With isotropic materials the d spacing of a crystal lattice, d, is assumed to vary linearly with sin2ψ. With textured materials the d vs sin2ψ relationship is nonlinear. This is due to the anisotropy of the elastic constants and their departure from a random distribution, or taking on a preferred orientation.

Effect of texture on the intrinsic dissolution behaviour of acetylsalicylic acid and tolbutamide compacts

2007 ◽  
Vol 40 (5) ◽  
pp. 857-864 ◽  
Author(s):  
Mikko Tenho ◽  
Jaakko Aaltonen ◽  
Paula Heinänen ◽  
Leena Peltonen ◽  
Vesa-Pekka Lehto
Keyword(s):  
Acetylsalicylic Acid ◽  
Random Distribution ◽  
Preferred Orientation ◽  
X Ray Diffraction ◽  
Intrinsic Dissolution ◽  
X Ray ◽  
Dissolution Studies ◽  
Dissolution Properties ◽  
Dissolution Behaviour ◽  
Attachment Energy

Preferred orientation of crystallites,i.e.texture, is a common result when a sample with an irregular habit of particles is compacted to form a tablet. Since texturization alters the random distribution of the crystal planes on the surface of the compacted sample, the dissolution properties of highly texturized tablets could differ from the properties of a tablet with a less preferred orientation. Three batches from both acetylsalicylic acid and tolbutamide were recrystallized using different crystallization parameters to obtain powders with different texturization behaviour. Several X-ray diffraction procedures were used to characterize the texture and other crystallographic properties of the samples. The intrinsic dissolution profiles were measured using the channel flow technique. In addition, the attachment energy of the crystal planes lying on the surface of the compacts was calculated theoretically. The results indicate that the most texturized compacts had a clearly lower intrinsic dissolution rate than the compacts with a lower degree of preferred orientation. By combining the results of the texture measurements with the calculated attachment energy values, the surface energies of the samples could be estimated and the estimated energy values were in agreement with the results of the dissolution studies. Moreover, it was found that by using the results of the texture measurements, the habit of the sample particles can be successfully predicted.

Intramolecular and Liquid Structures of Tetramethylurea Studied by Means of X-Ray Diffraction

1992 ◽  
Vol 47 (9) ◽  
pp. 1003-1010 ◽  
Author(s):  
T. Radnai ◽  
H. Ohtaki
Keyword(s):  
Gas Phase ◽  
Random Distribution ◽  
Structural Parameters ◽  
Diffraction Method ◽  
Methyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molecular Ordering ◽  
Amide Derivatives ◽  
Good Agreement

Abstract The intramolecular and liquid structures of tetramethylurea (TMU) were investigated by the liquid x-ray diffraction method. It is confirmed that in the liquid state the four methyl groups are out of the plane which is constructed by the O, C, and the two N atoms, the molecular structure being similar to what had been found in the gas phase. All structural parameters are in good agreement with those of TMU determined in the gas phase and with those of amide derivatives in the liquid phase. The liquid is characterized by a random distribution of molecules as predominant, but a weak molecular ordering characterized by approximately two intermolecular nonbonding Me ··· O distances at 340 pm is proposed

Chain Structure and Dynamic Mechanical Property of the Vinylidenefluoride and Chlorotrifluoroethylene Copolymers

2014 ◽  
Vol 1049-1050 ◽  
pp. 123-128
Author(s):  
Guo Ping Zeng ◽  
Chun Bo Yue ◽  
Ya Qing Weng ◽  
Ming Yu Wang ◽  
Heng Feng Li
Keyword(s):  
Mechanical Properties ◽  
Random Distribution ◽  
Dynamic Mechanical Properties ◽  
Chain Structure ◽  
Radical Copolymerization ◽  
Dynamic Mechanical Property ◽  
Diffraction Spectrum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dynamic Mechanical

A series of vinylidenefluoride (VDF) and chlorotrifluoroethylene (CTFE) copolymers were prepared by radical copolymerization, the chain elements structures of the copolymers were gain with the elemental analysis, and the crystal regions with X-ray diffraction spectrum. The effect of chain elements structure on the crystallinity and dynamic mechanical properties was discussed with the DMA analysis. The result shows: the increasing of the CTFE content decreases the chain elements structure of VDF-VDF, the random distribution of VDF-CTFE structure has a great effect on the crystallization properties and the dynamic mechanical properties. The increasing of CTFE content improves the storage modulus and the damping of copolymers in the amorphous copolymers, while the distribution of chain segments’ length gets narrower.

Distribution and Burgers vectors of dislocations in semiconductor wafers investigated by rocking-curve imaging

2005 ◽  
Vol 38 (1) ◽  
pp. 91-96 ◽  
Author(s):  
Daniel Lübbert ◽  
Claudio Ferrari ◽  
Petr Mikulík ◽  
Petra Pernot ◽  
Lukas Helfen ◽  
...  
Keyword(s):  
Large Scale ◽  
Random Distribution ◽  
High Spatial Resolution ◽  
Sample Surface ◽  
X Ray Diffraction ◽  
Semiconductor Wafer ◽  
Rocking Curve ◽  
X Ray ◽  
Dislocation Densities ◽  
Distribution Of Dislocations

The method called `rocking-curve imaging' (RCI) has recently been developed to visualize lattice imperfections in large crystals such as semiconductor wafers with high spatial resolution. The method is based on a combination of X-ray rocking-curve analysis and digital X-ray diffraction topography. In this article, an extension of the method is proposed by which dislocation densities in large-scale samples (semiconductor wafer crystals) can be quantified and their variation across the sample surface determined in an instrumentally simple way. Results from a nearly dislocation-free S-doped InP crystal and a semi-insulating GaAs are presented; both display a clearly non-random distribution of dislocations.

X-ray diffraction from one-dimensionally disordered 2H crystals undergoing solid state transformation to the 6H structure II. The deformation mechanism

1980 ◽  
Vol 369 (1739) ◽  
pp. 451-461 ◽  
Keyword(s):  
Solid State ◽  
Deformation Mechanism ◽  
Random Distribution ◽  
Exact Expression ◽  
X Ray Diffraction ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Diffraction Effects ◽  
Close Packed Layer

The 2H or AB Structure may be transformed to 6H or ABCACB structure if deformation faults occur preferentially after every third close-packed layer. The theory of X-ray diffraction from one-dimensionally disordered crystals undergoing the 2H → 6H structural transformation by such a deformation mechanism is developed. For this, it is necessary to consider that the faults are not distributed entirely at random but tend to occur in such a manner as to statistically create a 6H structure. An exact expression for the diffracted intensity for crystals undergoing the 2H → 6H transformation by the deformation mechanism has been obtained and the different observable diffraction effects have been predicted. These results are very different from those obtained of 2H crystals containing an entirely random distribution of deformation faults, especially for large fault probabilities.

HOLZ Rings in EBSD Patterns of the UFeB4 Compound: Association with a Random Distribution of Planar Defects

2013 ◽  
Vol 19 (5) ◽  
pp. 1204-1210 ◽  
Author(s):  
Marta Dias ◽  
Patrícia Almeida Carvalho ◽  
Isabel Cordeiro dos Santos ◽  
Olivier Tougait ◽  
Ladislav Havela ◽  
...  
Keyword(s):  
Random Distribution ◽  
X Ray Diffraction ◽  
Orientation Relation ◽  
Magnetic Studies ◽  
Electron Backscattered Diffraction ◽  
Defective Structure ◽  
Planar Defects ◽  
X Ray ◽  
Paramagnetic Behavior ◽  
Analogous Compound

AbstractThe UFeB4 phase present in different alloys of the B–Fe–U system was studied by powder X-ray diffraction (PXRD) and scanning electron microscopy complemented with energy-dispersive spectroscopy and electron backscattered diffraction (EBSD). The PXRD data showed that the ternary compound crystallized adopting essentially the YCrB4-type structure. However, microstructural observations revealed that under high undercooling conditions the UFeB4 phase exhibits a random distribution of defects parallel to, which are consistently associated with intense higher-order Laue zone rings in EBSD patterns. Indexation of the EBSD patterns showed that the defective structure is compatible with an intergrowth of YCrB4- and ThMoB4-type layers according to the (010)YCrB4//(110)ThMoB4 and [001]YCrB4//[001]ThMoB4 orientation relation previously reported for an analogous compound. Magnetic studies indicated that the annealed UFeB4 compound has a paramagnetic behavior in the 2–300 K temperature range.

Search for New Semiconductors for High Temperature Applications:The BaPb1-x BixO3 System

1998 ◽  
Vol 512 ◽  
Author(s):  
V. Ponnambalam ◽  
U. V. Varadaraju
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Single Phase ◽  
Random Distribution ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Linear Variation ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Power Factor

ABSTRACTBaPbl-xBixO3 phases with 0.6⋚ x⋚ 1.0 were synthesized by high temperature solid state reaction. Powder X-ray diffraction measurements show that all compositions are in single phase. Linear variation of lattice parameter is observed in BaPb1-xBixO3 with change in x indicating the random distribution of Pb in Bi sites. The activation energies for conduction of phases with x=0.8−0.6 obtained from ρ −T plots are same suggesting that the band gap does not change for compositions with x-0.8−0.6. The low activation energy obtained for BaBiO3 can be attributed to the structure of the compound. S versus (1000/T) data of x=1.0−0.8 exhibit a two-slope behavior. The orthorhombic to cubic phase transition could be the possible reason for the high power factor values of BaBiO3.

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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