Distinguishing Between Coherent Interdiffusion and Incoherent Roughness in Synthetic Multilayers Using X-Ray Diffraction

1992 ◽  
Vol 280 ◽  
Author(s):  
Z. Xu ◽  
Z. Tang ◽  
S. D. Kevan ◽  
Thomas Novet ◽  
David C. Johnson
Keyword(s):  
Domain Size ◽  
Dynamical Theory ◽  
Variable Degree ◽  
X Ray Diffraction ◽  
Density Profiles ◽  
Small Deviations ◽  
Diffraction Patterns ◽  
Electron Density Profiles ◽  
Subsidiary Maxima ◽  
Good Agreement

ABSTRACT:: We have developed a method to separate coherent interfacial interdiffusion from incoherent interfacial roughness by extending an electromagnetic dynamical theory to calculate the reflectivity of a multilayer having an arbitrary interfacial profile with a variable degree of randomness in the repeating layer thicknesses. We find that the intensity of the subsidiary maxima are extremely sensitive to incoherent roughness while the intensity of the Bragg maxima are largely determined by the interfacial electron density profiles. Experimental data are modeled in a manner similar to that used by Warren and Averback to determine domain size of crystallites. We divide the multilayer into coherent domains differing from one another by small deviations from the average layer thicknesses. The diffraction intensity from each of these domains is then added to obtain the experimental pattern. The diffraction spectra of a set of Pt/Co multilayers with similar layer thicknesses but prepared with different sputtering gases illustrates the ability to separate the effects of coherent interdiffusion from incoherent roughness. The extent of incoherent roughness obtained using this model to analyze the diffraction data of these Pt-Co multilayers is in good agreement with TEM and STM results from the same samples. The diffraction patterns could not be simulated with abrupt concentration profiles and the extent of interdiffusion was found to be correlated with the energy of reflected neutrals present during the synthesis of the multilayers.

scholarly journals Experimentally obtained and computer-simulated X-ray non-coplanar 18-beam pinhole topographs for a silicon crystal

2019 ◽  
Vol 75 (3) ◽  
pp. 483-488 ◽  
Author(s):  
Kouhei Okitsu ◽  
Yasuhiko Imai ◽  
Yoshitaka Yoda
Keyword(s):  
Silicon Crystal ◽  
Dynamical Theory ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Good Agreement

Non-coplanar 18-beam X-ray pinhole topographs for a silicon crystal were computer simulated by fast Fourier transforming the X-ray rocking amplitudes that were obtained by solving the n-beam (n = 18) Ewald–Laue dynamical theory (E-L&FFT method). They were in good agreement with the experimentally obtained images captured using synchrotron X-rays. From this result and further consideration based on it, it has been clarified that the X-ray diffraction intensities when n X-ray waves are simultaneously strong in the crystal can be computed for any n by using the E-L&FFT method.

scholarly journals Analysis of oscillatory rocking curve by dynamical diffraction in protein crystals

2018 ◽  
Vol 115 (14) ◽  
pp. 3634-3639 ◽  
Author(s):  
Ryo Suzuki ◽  
Haruhiko Koizumi ◽  
Keiichi Hirano ◽  
Takashi Kumasaka ◽  
Kenichi Kojima ◽  
...  
Keyword(s):  
Glucose Isomerase ◽  
Dynamical Theory ◽  
Protein Crystals ◽  
X Ray Diffraction ◽  
High Quality ◽  
Rocking Curve ◽  
Dynamical Diffraction ◽  
High Quality Protein ◽  
Good Agreement

High-quality protein crystals meant for structural analysis by X-ray diffraction have been grown by various methods. The observation of dynamical diffraction in protein crystals is an interesting topic because dynamical diffraction generally occurs in perfect crystals such as Si crystals. However, to our knowledge, there is no report yet on protein crystals showing clear dynamical diffraction. We wonder whether the perfection of protein crystals might still be low compared with that of high-quality Si crystals. Here, we present observations of the oscillatory profile of rocking curves for protein crystals such as glucose isomerase crystals. The oscillatory profiles are in good agreement with those predicted by the dynamical theory of diffraction. We demonstrate that dynamical diffraction occurs even in protein crystals. This suggests the possibility of the use of dynamical diffraction for the determination of the structure and charge density of proteins.

Evaluation of Reference X-ray Diffraction Patterns in the ICDD Powder Diffraction File

1990 ◽  
Vol 34 ◽  
pp. 369-376
Author(s):  
G. J. McCarthy ◽  
J. M. Holzer ◽  
W. M. Syvinski ◽  
K. J. Martin ◽  
R. G. Garvey
Keyword(s):  
Powder Diffraction ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Cd Rom ◽  
X Ray ◽  
Binary Oxides ◽  
Diffraction Patterns ◽  
Input Format ◽  
Good Agreement

AbstractProcedures and tools for evaluation of reference x-ray powder patterns in the JCPDSICDD Powder Diffraction File are illustrated by a review of air-stable binary oxides. The reference patterns are evaluated using an available microcomputer version of the NBS*A1DS83 editorial program and PDF patterns retrieved directly from the CD-ROM in the program's input format. The patterns are compared to calculated and experimental diffractograms. The majority of the oxide patterns have been found to be in good agreement with the calculated and observed diffractograms, but are often missing some weak reflections routinely observed with a modern diffractometer. These weak reflections are added to the PDF pattern. For the remainder of the phases, patterns are redetermined.

scholarly journals A comparison of EISCAT and Dynasonde measurements of the auroral ionosphere

1996 ◽  
Vol 14 (12) ◽  
pp. 1403-1412 ◽  
Author(s):  
K. J. F. Sedgemore ◽  
P. J. S. Williams ◽  
G. O. L. Jones ◽  
J. W. Wright
Keyword(s):  
Auroral Ionosphere ◽  
Incoherent Scatter Radar ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
Scatter Radar ◽  
Complementary Techniques ◽  
Electron Density Profiles ◽  
Ionospheric Sounding ◽  
Over Time ◽  
Good Agreement

Abstract. Incoherent-scatter radar and ionospheric sounding are powerful and complementary techniques in the study of the Earth's ionosphere. The work presented here involves the use of the Tromsø Dynasonde as a correlative diagnostic with the EISCAT incoherent-scatter radar. A comparison of electron-density profiles shows how a Dynasonde can be used to calibrate an incoherent-scatter radar and to monitor changes in the system. Skymaps of the direction of Dynasonde echoes are compared with EISCAT-derived density profiles to illustrate how a Dynasonde can be used to measure the drift velocity of auroral features. Vector velocities fitted to Dynasonde echoes are compared with EISCAT-derived plasma velocities. The results show good agreement when the data are taken during quiet to moderately active conditions and averaged over time scales of 30 min or more.

Theoretical and Experimental Study of the Diffraction Contrast on Magnetic Domain Walls

1982 ◽  
Vol 37 (5) ◽  
pp. 419-426 ◽  
Author(s):  
M. Polcarová ◽  
J. Brádler
Keyword(s):  
Experimental Study ◽  
Single Crystals ◽  
Domain Walls ◽  
Magnetic Domain ◽  
Dynamical Theory ◽  
X Ray Diffraction ◽  
X Ray ◽  
Magnetic Domain Walls ◽  
Integrated Intensities ◽  
Good Agreement

Dynamical theory of the X-ray diffraction on a crystal containing misfit boundary was applied to the interpretation of the contrast observed in X-ray topographs on 90° magnetic domain walls in single crystals of an Fe-Si alloy. The integrated intensities were computed for several cases corresponding to the actual conditions of experiments. Good agreement of theoretical and experi­mental results was obtained.

The Hinckley index for kaolinites

Clay Minerals ◽  
1988 ◽  
Vol 23 (3) ◽  
pp. 249-260 ◽  
Author(s):  
A. Plançon ◽  
R. F. Giese ◽  
R. Snyder
Keyword(s):  
Diffraction Pattern ◽  
Defect Structure ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Linear Fashion ◽  
Non Linear ◽  
Diffraction Patterns ◽  
Good Agreement

AbstractThe (02,11) X-ray diffraction band from a low-defect kaolinite from Cornwall (Hinckley index HI = 1·22) was examined to determine the defect structure. No combination of interlayer translations and admixing of dickite layers accurately modelled the observed diffraction pattern. Calculated diffraction patterns which gave a good agreement with the shape, position, and intensity of the observed peaks, uniformly had inter-peak intensities which were too weak. By treating the kaolinite as a mixture of low-defect (HI = 1·76) and moderate-defect (HI = 0·29) kaolinites, the agreement between the observed and calculated patterns was improved substantially. The existence of a mixture of two kaolinites was also found for a number of low-defect samples (HI > 0·4) from Georgia and Cornwall, and may be of even wider occurrence. The HI, which is very sensitive to the inner-peak intensities, does not estimate the types or abundances of various structural defects (the classical “crystallinity”), but is related directly, in a non-linear fashion, to the proportions of the two kinds of kaolinite which are present in the sample.

X-ray diffraction studies of oriented lipid bilayers

1995 ◽  
Vol 73 (5-6) ◽  
pp. 209-218 ◽  
Author(s):  
J. Katsaras
Keyword(s):  
Lipid Bilayers ◽  
Diffraction Data ◽  
Phase Problem ◽  
X Ray Diffraction ◽  
Density Profiles ◽  
X Ray ◽  
Oriented Lipid Bilayer ◽  
Electron Density Profiles ◽  
Subgel Phase ◽  
Phase Phase

This brief review of the X-ray diffraction technique used to study oriented lipid bilayer systems is primarily intended to demonstrate to the nonspecialist in the lipid field the amount of detailed information that can be obtained simply by visually inspecting the diffraction pattern and making some measurements with a ruler and protractor. The information that can be extracted from X-ray diffraction data is illustrated by selected examples of our most recent work.Key words: X-ray diffraction, oriented multibilayers, electron density profiles, subgel phase, phase problem.

Synchrotron X-Ray Diffraction Study of the Surface Layer in Poled Ceramic BaTiO3#

1996 ◽  
Vol 453 ◽  
Author(s):  
D. Balzar ◽  
P. W. Stephens ◽  
H. Ledbetter ◽  
J. Li ◽  
M. L. Dunn
Keyword(s):  
Surface Layer ◽  
Domain Switching ◽  
Domain Size ◽  
Peak Shift ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inhomogeneous Strain ◽  
Excessive Strain ◽  
Average Domain Size ◽  
Diffraction Patterns

AbstractBoth unpoled and poled BaTiO3 were studied by laboratory and synchrotron x-ray sources. The shorter-wavelength synchrotron radiation was used to probe deeper below the specimen surface. Diffraction patterns revealed a distinctive surface layer of the same tetragonal structure as the main BaTiO3 fraction. A sin2 Ψ analysis of peak shift confirmed that no measurable change of elastic strain occurs upon poling. This indicates that poling may induce excessive strain that was relieved by microcracking or that a majority of domains reverse orientation. However, domain switching and possible microcracking may induce inhomogeneous strain (microstrain) and alter domain-size distribution. Line-broadening analysis showed large anisotropy of both coherently diffracting domain size and microstrain. The poled specimen shows a larger microstrain and smaller average domain size, which indicates possible effects of microcracking and additional defects created during poling.

An Application of Multigrain Approaches to the Structural Solution of Grains from Polycrystalline Samples

2019 ◽  
Vol 288 ◽  
pp. 119-123 ◽  
Author(s):  
Jav Davaasambuu ◽  
Jon Wright ◽  
Henning O. Soerensen ◽  
Soeren Schmidt ◽  
Henning F. Poulsen ◽  
...  
Keyword(s):  
Structural Refinement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Experimental Parameters ◽  
Resolution Level ◽  
Diffraction Patterns ◽  
The Individual ◽  
Individual Grains ◽  
Comparison Of The Results ◽  
Good Agreement

The overlap of diffraction spots from different grains was investigated to understand the influence of experimental factors on the x-ray diffraction data quality and to optimize the experimental parameters for data collection on polycrystalline samples. Diffraction patterns for photoactive polycrystals were indexed and sorted with respect to grains using multigrain approaches. The indexing of diffraction spots and the identification of grains for tetrathiafulvalene-p-chloranil samples were performed using the ImageD11, GrainSpotter, GRAINDEX and Cell_now programs. In many cases, comparison of the results from these programs shows good agreement. For the individual grains from polycrystalline samples, the crystal structure was solved and refined using the SHELXTL program. After the structural refinement of the grains, the best and the average R1 values were 1.93% and 2.06%, respectively, which are on a comparable resolution level with that obtained from the x-ray single crystal measurements.

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