Continuous-scan capability at SSRL and applications to X-ray diffraction

2016 ◽  
Vol 23 (4) ◽  
pp. 909-918 ◽  
Author(s):  
Chunlei Li ◽  
Andrew M. Kiss ◽  
Douglas G. Van Campen ◽  
Alex Garachtchenko ◽  
Yuriy Kolotovsky ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
X Ray Diffraction ◽  
Scanning Method ◽  
X Ray ◽  
Motor Controller ◽  
Acceleration And Deceleration ◽  
Data Points ◽  
Total Measurement Time ◽  
Zno Powder ◽  
Deceleration Time

Typical X-ray diffraction measurements are made by moving a detector to discrete positions in space and then measuring the signal at each stationary position. This step-scanning method can be time-consuming, and may induce vibrations in the measurement system when the motors are accelerated and decelerated at each position. Furthermore, diffraction information between the data points may be missed unless a fine step-scanning is used, which further increases the total measurement time. To utilize beam time efficiently, the motor acceleration and deceleration time should be minimized, and the signal-to-noise ratio should be maximized. To accomplish this, an integrated continuous-scan system was developed at the Stanford Synchrotron Radiation Lightsource (SSRL). The continuous-scan system uses an in-house integrated motor controller system and counter/timer electronics.SPECsoftware is used to control both the hardware and data acquisition systems. The time efficiency and repeatability of the continuous-scan system were tested using X-ray diffraction from a ZnO powder and compared with the step-scan technique. Advantages and limitations of the continuous-scan system and a demonstration of variable-velocity continuous scan are discussed.

Effect of Sintering Temperature on Microstructure and Electrical Properties of Nanozinc Oxide Varistor

2011 ◽  
Vol 495 ◽  
pp. 190-193 ◽  
Author(s):  
Mehdi Mirzayi ◽  
Mohammad Hoseen Hekmatshoar ◽  
Abdolazim Azimi
Keyword(s):  
Electrical Properties ◽  
Sintering Temperature ◽  
Voltage Characteristic ◽  
X Ray Diffraction ◽  
Current Voltage Characteristic ◽  
X Ray ◽  
Current Voltage ◽  
Polyacrylamide Gel Method ◽  
Zno Powder ◽  
Scanning Electron

Nanometer-sized ZnO powder was synthesized at low decomposing temperature by polyacrylamide-gel method where Acrylamide was used as monomer, and N,N-methylene-bisacrylamide as lattice reagent. The characteristic of powders were studied by X-ray diffraction and scanning electron microscope (SEM). The results indicated uniform distribution of nanoZnO particles. Also electrical properties were investigated at different sintering temperatures of 800, 900 and 1000 ° C. It was observed that increase in sintering temperature, resulted in increase in the grain size of the varistor ceramics. The observed nonlinearity in current – voltage characteristic was explained by the existence of potential barrier at the grain boundaries and lowering of the barriers.

A full-pattern fitting algorithm for energy-dispersive X-ray diffraction

2003 ◽  
Vol 36 (5) ◽  
pp. 1123-1127 ◽  
Author(s):  
Yu-Hui Dong ◽  
Jing Liu ◽  
Yan-Chun Li ◽  
Xiao-Dong Li
Keyword(s):  
High Pressure ◽  
Energy Dispersive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Fitting Algorithm ◽  
Diffraction Angle ◽  
Data Points ◽  
Diffraction Peaks ◽  
Very High

A full-pattern fitting algorithm for energy-dispersive X-ray diffraction is proposed, especially for high-pressure X-ray diffraction studies. The algorithm takes into account the errors in measuring the energy and the diffraction angle. A lognormal function is introduced to represent the background. All the peaks that are detectable in the diffraction spectra, including fluorescence and diffraction peaks, are considered together. Because all the data points in the spectra are used, the accuracy of the cell parameters obtained by this method is very high. This is very helpful in the analysis of the equation of state and the identification of new phases under high pressure.

Enhancing the Signal-to-Noise Ratio of X-ray Diffraction Profiles by Smoothed Principal Component Analysis

2005 ◽  
Vol 77 (20) ◽  
pp. 6563-6570 ◽  
Author(s):  
Zeng Ping Chen ◽  
Julian Morris ◽  
Elaine Martin ◽  
Robert B. Hammond ◽  
Xiaojun Lai ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Signal To Noise Ratio ◽  
Principal Component ◽  
Component Analysis ◽  
X Ray Diffraction ◽  
Signal To Noise ◽  
X Ray ◽  
Noise Ratio

Waveguide-enhanced scattering from thin biomolecular films

2002 ◽  
Vol 35 (2) ◽  
pp. 163-167 ◽  
Author(s):  
F. Pfeiffer ◽  
U. Mennicke ◽  
T. Salditt
Keyword(s):  
Lipid Bilayers ◽  
Signal To Noise Ratio ◽  
Acyl Chain ◽  
Grazing Incidence ◽  
Waveguide Structure ◽  
X Ray Diffraction ◽  
Signal To Noise ◽  
X Ray ◽  
Grazing Incidence Diffraction ◽  
Chain Ordering

An X-ray diffraction experiment on multilamellar membranes incorporated into an X-ray waveguide structure is reported. In the device, the lipid bilayers are confined to one side by the silicon substrate and to the other side by an evaporated thin metal cap layer. Shining a highly brilliant X-ray beam onto the system, resonantly enhanced, precisely defined and clearly distinguishable standing-wavefield distributions (modes) are excited. The in-plane structure of the acyl chain ordering is then studied by grazing incidence diffraction under simultaneously excited modes. A significant gain in signal-to-noise ratio as well as enhanced spatial resolution can be obtained with such a setup.

Stress in Ag/Ni Multilayers: A Comparison of Specimen-Curvature and X-Ray Diffraction Methods

1997 ◽  
Vol 472 ◽  
Author(s):  
P. Gergaud ◽  
S. Labat ◽  
H. Yang ◽  
A. Bottger ◽  
P. SandstrÖm ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Intrinsic Stress ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Scanning Method ◽  
X Ray ◽  
Integrated Devices ◽  
Curvature Measurement ◽  
Very High

ABSTRACTMultilayers and superlattices are of great industrial interest because of their specific properties (magnetic, electronic, tribological…). Multilayers stacking are often in a very high state of intrinsic stress (some GPa) and for reliable integrated devices to be made it is capital to control and understand these intrinsic as well as extrinsic stresses. The objective of the present work is therefore the understanding of the origin of stresses and strains in multilayered metallic materials. Of course, a comparison of the different techniques which can be used for stress determination is a necessary first step of this study. In this aim, we have studied Ag/Ni multilayers, Ag and Ni thin films and Ag/Ni bilayers obtained by sputtering. The stresses have been determined via curvature measurement using both a laser scanning method and X-ray diffraction rocking curves technique, and via X-ray diffraction measurement of several d-spacings which act as in-situ strain gauges (also called the sin2ψ method and related methods). The obtained results from these different techniques are discussed in terms of accuracy, reproducibility and advantages / drawbacks. The obtained stresses from these methods cannot be directly compared and a specific discussion is developed around the relation between the measured strains and stresses and the microstructure of the materials.

Errors in Residual Stress Measurements due to Random Counting Statistics

1970 ◽  
Vol 14 ◽  
pp. 377-388 ◽  
Author(s):  
C. J. Kelly ◽  
M. A. Short
Keyword(s):  
Residual Stress ◽  
Standard Deviation ◽  
Stress Measurement ◽  
Mathematical Expression ◽  
X Ray Diffraction ◽  
Intensity Maximum ◽  
X Ray ◽  
Diffraction Angle ◽  
Data Points ◽  
Counting Statistics

AbstractThe measurement of residual stress, using X-ray diffraction techniques, is based on the change in diffraction angle determined for the Intensity maximum of some suitable reflection from the sample when this is placed consecutively with its surface at two different angles to the diffracting planes. These diffraction angles may be obtained in a variety of ways, but are most often calculated from measurements of three X-ray diffraction intensities at angles selected in the immediate vicinity of the peak maximum at each sample angle and fitting each set of data to a parabolic curve. A simple mathematical expression may be derived relating the diffraction angles, and hence the residual stress, to the measured X-ray intensities; there will, however, be statistical errors in the calculated diffraction angles due to random counting errors in the measurement of the X-ray diffraction intensities. From the expression relating the residual stress to the X-ray intensities an equation has been derived giving the standard deviation in the residual stress due to random counting errors. In addition, a simple approximation has been obtained from this equation showing that the standard deviation is decreased by increasing the number of counts accumulated for each X-ray intensity measurement and by increasing the size of the angular increments between the data points. It will also be shown that, using the approximation, it is possible to estimate in advance the number of accumulated counts at each point necessary to attain a desired standard deviation in a residual stress measurement.

scholarly journals FELIX: an algorithm for indexing multiple crystallites in X-ray free-electron laser snapshot diffraction images

2017 ◽  
Vol 50 (4) ◽  
pp. 1075-1083 ◽  
Author(s):  
Kenneth R. Beyerlein ◽  
Thomas A. White ◽  
Oleksandr Yefanov ◽  
Cornelius Gati ◽  
Ivan G. Kazantsev ◽  
...  
Keyword(s):  
Free Electron Laser ◽  
Signal To Noise Ratio ◽  
X Ray Diffraction ◽  
Signal To Noise ◽  
Monoclinic Crystal ◽  
Slight Tendency ◽  
X Ray ◽  
Serial Crystallography ◽  
Diffraction Patterns ◽  
Novel Algorithm

A novel algorithm for indexing multiple crystals in snapshot X-ray diffraction images, especially suited for serial crystallography data, is presented. The algorithm, FELIX, utilizes a generalized parametrization of the Rodrigues–Frank space, in which all crystal systems can be represented without singularities. The new algorithm is shown to be capable of indexing more than ten crystals per image in simulations of cubic, tetragonal and monoclinic crystal diffraction patterns. It is also used to index an experimental serial crystallography dataset from lysozyme microcrystals. The increased number of indexed crystals is shown to result in a better signal-to-noise ratio, and fewer images are needed to achieve the same data quality as when indexing one crystal per image. The relative orientations between the multiple crystals indexed in an image show a slight tendency of the lysozme microcrystals to adhere on (\overline 110) facets.

scholarly journals Graphene as a protein crystal mounting material to reduce background scatter

2013 ◽  
Vol 46 (5) ◽  
pp. 1501-1507 ◽  
Author(s):  
Jennifer L. Wierman ◽  
Jonathan S. Alden ◽  
Chae Un Kim ◽  
Paul L. McEuen ◽  
Sol M. Gruner
Keyword(s):  
Signal To Noise Ratio ◽  
Protein Crystal ◽  
Protein Crystals ◽  
Graphene Sheets ◽  
X Ray Diffraction ◽  
Signal To Noise ◽  
X Ray ◽  
Background Reduction ◽  
Diffraction Imaging ◽  
Unit Dose

The overall signal-to-noise ratio per unit dose for X-ray diffraction data from protein crystals can be improved by reducing the mass and density of all material surrounding the crystals. This article demonstrates a path towards the practical ultimate in background reduction by use of atomically thin graphene sheets as a crystal mounting platform for protein crystals. The results show the potential for graphene in protein crystallography and other cases where X-ray scatter from the mounting material must be reduced and specimen dehydration prevented, such as in coherent X-ray diffraction imaging of microscopic objects.

Investigation on Nano-Sized ZnO Powder Doped with Al3+ Prepared by Sol-Gel Method

2012 ◽  
Vol 621 ◽  
pp. 3-7
Author(s):  
Yu Xiong ◽  
Ji Zheng ◽  
Song Lin Li ◽  
Xue Jia Liu ◽  
Lu Liang
Keyword(s):  
Electron Microscope ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nano Powder ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Doped Zno ◽  
Zno Powder ◽  
Tin Tetrachloride

Al3+-doped ZnO nano-powder was prepared by sol-gel process, using tin tetrachloride and titanium tetrachloride as starting materials. The crystallinity and purity of the powder were analyzed by X-ray diffraction spectrometer (XRD). And the size and distribution of Al3+-doped ZnO grains were studied using transmission electron microscope (TEM) and scanning electron microscope (SEM). The results showed that the Al3+ was successfully doped into the crystal lattice of tin oxide and that the electric conductivity of Al3+-doped ZnO sample was improved significantly.

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