The macroscopic response of polycrystalline materials to loading depends on both the spatial distribution of strain and the variation of microtexture on the scale of 100 μm. Nondestructive measurements are needed if the three-dimensional evolution of strain is to be studied. This paper describes approaches for high resolution synchrotron polychromatic x-ray diffraction tomography of polycrystalline materials. Preliminary experiments are reported on partially cracked compact tension samples of Al-Li 2090 and on model samples of randomly-packed, millimeter-sized pieces of Si wafers. Polychromatic beams collimated to 100 μm diameter have been used, and the distribution of diffracted intensity has been collected on high resolution x-ray film as well as on image storage plates. The depths of diffracting volume elements are determined from the changes in the spatial distribution of diffracted intensity with varying sample to detector separation.

Synchrotron white beam X-ray topography, along with optical microscopy and scanning electron microscopy, has been used to characterize structural defects which are potentially detrimental to device performance in PVT 6H-SiC single crystals. Line defects running along the [0001] axis, known as “micropipes”, were studied extensively. Detailed analysis of topographic image contrast associated with “micropipes”, based on the kinematical theory of X-ray diffraction, established that the so-called “micropipes” are screw dislocations with large Burgers vectors.

Dislocation velocities have been measured in both lightly and heavily HCl-doped ice single crystals using synchrotron-based, monochromatic X-ray topography. In the temperature range −10°C to −30°C, a concentration of ˜1 × 10−6M was found not to affect the mobility of either 60° or screw basal dislocations, confirming the earlier observations of C. Shearwood and R. W. Whitworth [Philosophical Magazine A65, 1992, 85]. However, heavier doping (˜1.9 × 10−4M) increased the basal dislocation velocity, compared to pure ice, by a factor of 2.6 at −16.4°C.

We describe how the scanning transmission x-ray microscope at Brookhaven National Laboratory can be used to investigate the bulk characteristics of polymeric materials with chemical sensitivity at a spatial resolution of about 50 nm. We present examples ranging from unoriented multiphase polymers to highly oriented Kevlar fibers. In the case of oriented samples, a dichroism technique is used to determine the orientation of specific chemical bonds. Extension of the technique to investigate surfaces of thick samples is discussed.

The Second Generation Scanning Photoemission Microscope at the beamline X1A of the National Synchrotron Light Source (NSLS), X1A SPEM II, is designed for spatially resolved elemental and chemical analysis by X-ray Photoelectron Spectroscopy (XPS) on material surfaces. Based on Fresnel Zone Plate (ZP) microfocusing techniques with the use of a bright and coherent photon source, this microscope is capable of acquiring XPS spectra from a small area irradiated by the focused beam and taking element-specific (using photopeaks) or chemical-state-specific (by detecting the chemical core level shifts) images with a spatial resolution defined by the focused spot size.

The use of synchrotron x-ray fluorescence microscopy to study the composition and homogeneity of laser deposited films of calcium-nickel-potassium oxides is described. Experimental conditions for preparing the films are given, and the results are discussed with respect to the x-ray fluorescence data concerning the distribution of the three metals in the films.

Defect structures in Lely SiC single crystals have been studied using synchrotron white beam X-ray topography. Basal plane dislocations and stacking faults probably generated during post-growth cooling are clearly revealed. For both perfect dislocations and partial dislocations bounding the stacking faults, Burgers vectors and line directions are determined from contrast extinction analysis as well as projected direction analysis on different topographic images. The fault planes and fault vectors of the stacking faults were determined using contrast extinction analysis. Possible dislocation generation mechanisms are briefly discussed.

White-beam synchrotron X-ray topography has been used to study the circular, prismatic, [0001] dislocation loops which are commonly-observed on the (0001) plane in polycrystalline, freshwater ice. A new method, involving detailed analyses of the effects of beam divergence on the loop images, has been developed to determine whether a loop is of vacancy or interstitial type. In an 0002 image, one half of a loop (projected as an ellipse) appears as a single image and the other half as a double image. Experimentally, it was found that the 0002 vector drawn from the center of a loop passes through the single image if the loop is of vacancy-type and through the double image if a loop is of interstitial-type. This method of loop characterization was confirmed by performing theoretical analyses of both the dislocation image widths and their strain fields.

SiC device configurations comprising various polytypes have been analyzed using synchrotron white beam x-ray topography with the aid of computer simulation. Diffracted intensity maps for the various polytypes and their combinations in various diffraction geometries, including transmission, reflection, grazing-reflection and back-reflection are generated. This method is used to determine the structures of SiC devices fabricated via CVD epilayer growth of nominally 3C-SiC or 6H-SiC, or 6H-SiC substrates grown by the Lely technique. The work indicates that those devices which were initially considered to be of 3C structure also contain some 6H structure. Defect structures associated with the polytype configurations are also presented.