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Special Techniques
Published in Harry E. Martz, Clint M. Logan, Daniel J. Schneberk, Peter J. Shull, X-Ray Imaging, 2016
Harry E. Martz, Clint M. Logan, Daniel J. Schneberk, Peter J. Shull
X-ray topography is not primarily concerned with the study of surfaces. The full title, x-ray diffraction topography, is much clearer since it indicates that the topography being studied is that of diffracting planes within a crystal, not the topography of the exterior features. The contours of the crystal surfaces are important in determining the contrast on x-ray topographs, but it is somewhat secondary in importance to the contours of the crystal lattice planes. When used to observe dislocations, topography is used to study the lattice planes around defects. The irradiance of the x-rays diffracted from the deformed planes differs from the irradiance diffracted by a perfect crystal forming an image of the defects. Topography is not a point probe, and the interpretation of the observed contrast is not trivial.
MicroCT Systems and Their Components
Published in Stuart R. Stock, MicroComputed Tomography, 2019
Use of an asymmetrically cut crystal (see Fig. 2.9), positioned between sample and x-ray area detector and set to diffract the monochromatic synchrotron radiation incident on the sample, has been demonstrated to reject scatter and improve sensitivity as well as to provide, through beam spreading, magnification of the x-ray beam prior to its sampling by the x-ray detector (Sakamoto, Suzuki et al. 1988, Suzuki, Usami et al. 1988, Kinney, Bonse et al. 1993). This is an adaptation of a commonly used method in x-ray diffraction topography that allows one to overcome limitations of the detector; that is, to approach resolutions inherent to the x-ray source.
MicroCT Systems and Their Components
Published in Stuart R. Stock, MicroComputed Tomography, 2018
Use of an asymmetrically cut crystal (see Figure 2.9), positioned between the sample and x-ray area detector and set to diffract the monochromatic synchrotron radiation incident on the sample, has been demonstrated to reject scatter and improve sensitivity as well as to provide, through beam spreading, magnification of the x-ray beam prior to its sampling by the x-ray detector (Sakamoto et al., 1988; Suzuki et al., 1988; Kinney et al., 1993). This is an adaptation of a commonly used method in x-ray diffraction topography that allows one to overcome limitations of the detector, that is, to approach resolutions inherent to the x-ray source.
Visualizing local bending of lattice planes by extending two-azimuth synchrotron X-ray diffraction datasets to asymmetric reflection
Published in Science and Technology of Advanced Materials: Methods, 2023
X-ray diffraction topography (XRDT) is a nondestructive technique for characterizing the crystal quality of a single crystal mainly processed into plate shapes. When we study the microstructure of a localized area, XRDT is powerful for observing defect-derived crystalline imperfections, or lattice strain fields, originating from structural defects, dislocations, and stacking faults. From a macroscopic viewpoint, it is important to know the shapes of lattice planes and the distributions of lattice constants over an entire sample to improve crystal quality. Lattice parameter distributions can be affected by inhomogeneities in chemical composition during sample growth. XRDT has been extended to a variety of methods using laboratory X rays and synchrotron X rays using a white beam or monochromatic one.
The micro- to nano-scale dislocation mechanics of (001) MgO crystal hardness
Published in Philosophical Magazine Letters, 2021
An early description of etched dislocation rosette patterns produced at aligned diamond pyramid indentations put into an MgO (100) crystal surface was given by Keh [1]. Armstrong and Wu [2] produced scanning electron microscope (SEM) and X-ray diffraction topography measurements for two orientations of diamond pyramid indentations made either with the surface-projected diagonal edges parallel to the <010> or <011> directions on the (100) crystal surface. Figure 1 was developed in a study to relate such information to creation of energy localisation in ammonium perchlorate and inert crystals such as MgO [3,4].
Experimental and numerical study on the thermal and hydrodynamic characteristics of non-Newtonian decaying swirl flows
Published in Journal of Dispersion Science and Technology, 2019
Ehsan Taheran, Kourosh Javaherdeh
The novel non-Newtonian drilling nanofluid is an equal volume mixture of silver/water nanofluid and a biological water-soluble oil. Nanofluid is formulated with silver nitrate as a source for silver nanoparticles, sodium borohydride and hydrazine as reducing agents and polyvinyl pyrrolidone (PVP) as surfactant by one-step method.[22]Figure 1 represents the graph of nanoparticles size distribution in nanofluid, measured by dynamic light scattering. X-ray diffraction topography pattern of the Ag nanofluid sample is shown in Figure 2 and TEM image of Ag nanoparticles dispersed in colloidal solution is displayed in Figure 3.