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High-energy X-rays (high-energy + x-ray)
Terms modified by High-energy X-rays Selected AbstractsDepth-Resolved Porosity Investigation of EB-PVD Thermal Barrier Coatings Using High-Energy X-raysJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2004Anand A. Kulkarni Demands for designing prime reliant, energy-efficient, and high-performance thermal barrier coatings (TBCs) in gas turbines have led to a growing interest toward comprehensive microstructural characterization. Here we investigate the novel use of high-energy X-rays for small-angle X-ray scattering (SAXS), together with wide-angle scattering and radiography, for the depth-resolved characterization of TBCs grown by electron beam physical vapor deposition (EB-PVD). The coating microstructure is found to consist of columns perpendicular to the substrate, extending through the thickness, with a [001] growth texture and significant intercolumnar porosity. In addition, overshadowing effects during deposition together with gas entrapment give rise to nanoscale intracolumnar porosity consisting of featherlike and globular pores. Radiography showed an increase in the total porosity, from 15% near the substrate to 25% near the coating surface, which is ascribed to an increase in the intercolumnar spacing at the top of the coating. By contrast, the small-angle scattering studies, which are sensitive to fine features, showed the pore internal surface area to be greatest near the substrate. [source] Supercooled Barium Boric Oxide Melts: X-Ray Diffraction Measurements and Glass FormationJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2007Seiichi Matsumura It is well-known that oxide melts easily form a glass state from a supercooled state; however, it is difficult for some oxides to transform to the glass state from the corresponding supercooled state. ,-BaB2O4 (,-BBO) crystals are important materials for laser applications. The ,-BBO crystal easily grows from the supercooled melt, and it is therefore difficult to form the BBO glass state. We attempted to make BBO glass by a containerless technique using the conical nozzle gas-jet levitation (CNL) method. We were successful in making BBO glass with a diameter of 2 mm from a highly supercooled melt without rapid quenching. In order to clarify the phase selection mechanism of the BBO melt, we performed high-energy X-ray (113.6 keV) diffraction experiments on the glassy and supercooled liquid BBO using the CNL technique at the BL04B2 beamline of SPring-8. From these experiments, the structure factor S(Q) of BBO glasses and supercooled melts were found to have almost the same features. From these S(Q), we obtained the radial distribution function T(r)=4,rg(r). The analysis also showed that BBO glass and the BBO-supercooled melt have the same short-range distances. For phase selection between crystalline and glassy phases, we discuss a structure model of the BBO melt, including medium range structure based on the short-range structure obtained in this experiment. [source] Elastic deformations in a perfect bulk Si crystal studied by high-energy X-raysJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2009Alexander Gröschel Long-range strain fields induced in highly perfect bulk crystals during the manufacturing process significantly affect the quality and may even lead to spontaneous fracturing. Obviously a quantitative assessment of these deformations is crucial. A possible means is to examine the diffraction of X-rays by strained crystals, as the deformations bear on the diffraction characteristics of such crystals. In this report a quantitative examination of the diffraction characteristics of a perfect silicon bulk crystal with long-range strain fields in a well defined geometry is presented. The experiments were carried out using a high-energy X-ray laboratory source. By simulating the elastic deformation of the crystal by a finite element program the strain fields of the diffracting crystal are accessed. From these, simulated data values for integrated intensities can be derived on the basis of the dynamical diffraction theory for slightly distorted crystals. The theoretical calculations show good agreement with the experimental measured values. The smallest deformation yielding a noticeable change of the integrated intensity can be associated with a bending radius of the diffracting lattice planes of 16,km. [source] A focusing Laue diffractometer for the investigation of bulk crystalsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 4 2008Matthias Stockmeier A focusing Laue diffractometer for high-energy X-rays of up to 300,keV in a laboratory environment is presented. The long attenuation length for X-ray energies above 50,keV allows for the non-destructive investigation of structural issues and bulk properties of single crystals. Furthermore, massive sample environments such as high-temperature furnaces can be used more easily. With an area detector, anisotropic mosaicities or crystallite structure become visible without any rocking movement of the sample. [source] Quantitative high-pressure pair distribution function analysisJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2005John B. Parise The collection of scattering data at high pressure and temperature is now relatively straightforward thanks to developments at high-brightness synchrotron radiation facilities. Reliable data from powders, that are suitable for structure determination and Rietveld refinement, are routinely collected up to about 30,GPa in either a large-volume high-pressure apparatus or diamond anvil cell. In those cases where the total elastic scattering is of interest, as it is in the case of nano-crystalline and glassy materials, technical developments, including the use of focused high-energy X-rays (>80,keV), are advantageous. Recently completed experiments on nano-crystalline materials at the 1-ID beamline at the Advanced Photon Source suggest that quantitative data, suitable for pair distribution function analysis, can be obtained. [source] Plane-wave X-ray topography and its application at SPring-8JOURNAL OF SYNCHROTRON RADIATION, Issue 3 2002Satoshi Iida Plane-wave X-ray topography experiments were carried out at a 200,m-long beamline, BL20B2, at SPring-8. Relatively high-energy X-rays of 30,keV with an angular divergence of about 0.01,arcsec were produced by using only one collimator crystal. FZ-Si and CZ-Si wafers were characterized in transmission geometry (Laue case). Clear oscillatory profiles in rocking curves of the FZ-Si crystal were observed. Plane-wave topographic images of dislocations, growth striations and grown-in microdefects in the CZ-Si crystals were obtained. The dependence of the topographic images of the lattice defects on the sample,photoplate distance was also studied. [source] Depth-Resolved Porosity Investigation of EB-PVD Thermal Barrier Coatings Using High-Energy X-raysJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2004Anand A. Kulkarni Demands for designing prime reliant, energy-efficient, and high-performance thermal barrier coatings (TBCs) in gas turbines have led to a growing interest toward comprehensive microstructural characterization. Here we investigate the novel use of high-energy X-rays for small-angle X-ray scattering (SAXS), together with wide-angle scattering and radiography, for the depth-resolved characterization of TBCs grown by electron beam physical vapor deposition (EB-PVD). The coating microstructure is found to consist of columns perpendicular to the substrate, extending through the thickness, with a [001] growth texture and significant intercolumnar porosity. In addition, overshadowing effects during deposition together with gas entrapment give rise to nanoscale intracolumnar porosity consisting of featherlike and globular pores. Radiography showed an increase in the total porosity, from 15% near the substrate to 25% near the coating surface, which is ascribed to an increase in the intercolumnar spacing at the top of the coating. By contrast, the small-angle scattering studies, which are sensitive to fine features, showed the pore internal surface area to be greatest near the substrate. [source] | ||||||||||