European Powder Diffraction EPDIC 8

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Authors: S. Battaglia, F. Mango
Abstract: Thermal expansion coefficients (TEC) of some metallic samples and rocks, along with one sample of amorphous silica, were determined by means of a standard X-ray diffractometer without any modification to the equipment. Only the sample holder was modified in order to fix the sample within the standard goniometer and avoid heat dispersion into the chamber during heating of the sample. The latter was achieved by the Joule effect through a thermo-coaxial wire coil wrapped directly around the bulk sample. A thin metal foil, aluminium in our case, was placed on the flat surface of the cylinder sample. The variations in Al peak position recorded at various sample temperatures were related directly to the dilatation of the material supporting the thin foil.
Authors: Kurt Erlacher, R. Görgl, Jozef Keckes, Hannes F. Jakob, L. Bruegemann, P. Doppler, A. Bergmann, Heinz Leitner, S. Marsoner, Peter Fratzl
Abstract: A laboratory system (NanoSTAR) based on a combination of specially designed X-ray multilayer optics (Göbel Mirrors) with optical bench, pinhole collimators, sample changer and primary beam stop as well as a two dimensional multiwire detector (HI-STAR) was equipped with a sealed cobalt X-ray tube. This solution was chosen because the CoKα has a wavelength close to that of copper but allows to overcome the problem of excessive fluorescence in Fe-samples. Various measurements were performed using this configuration of the NanoSTAR to demonstrate the performance of SAXS using cobalt radiation. A comparison is given to the primary beam intensity of the NanoSTAR with Co radiation with respect to the Cu radiation. Examples for the use of the Co radiation are given by investigating the coarsening behavior of precipitates in several Fe-based alloys. The change in size and shape of these precipitates under different heat treatment conditions are characterized.
Authors: Bonglea Kim, Boris Verman, Licai Jiang
Abstract: X-ray diffraction systems based on a microfocusing X-ray source and multilayer side-by-side optics are suitable for X-ray diffraction studies in a variety of fields, such as protein crystallography, due to their compactness and low cost in maintenance. However, new problems can occur, such as intensity instability induced by source position drifting. Various investigations for the reasons and the consequences of the instability are presented in this paper. Feasible solutions and suggestions are given to obtain more stable system performance.
Authors: D. Šimek, Radomír Kužel, J. Kub, F. Kunc
Abstract: Textured thin film of PbTiO3 on glass and both textured and stressed films of TiB2 on iron substrate were investigated by two-dimensional reciprocal space mapping. The texture and residual stress parameters were found by fitting of the measured intensity in the reciprocal space map by the simulated data. Two different types of texture were found in TiB2 for different values of residual stress. The relevance of resulting parameters was checked using different models. Simulation of the data involved a proper empirical texture correction, the Pearson VII profile function, the irradiated volume correction giving a possibility of the film thickness determination, the background, and other correction factors (Lorentz, polarisation).
Authors: Boris Verman, Srivatsan Seshadri, Bonglea Kim
Abstract: A simple analytical approach is given to calculate the performance of parabolic mirrors for various wavelengths. Expressions are given for the efficiency of the parabolic mirror system and insertion gain. As examples, parameters for some mirrors for CuKα and MoKα radiation are calculated.
Authors: A. Zięba, W. Dąbrowski, P. Gryboś, W. Pawroźnik, J.R. Słowik, T. Stobiecki, K. Świentek, P. Wiącek
Abstract: Silicon strip detectors represent a new class of one-dimensional position-sensitive single photon counting devices. They allow a reduction of measurement time at the powder diffractometers by a factor up to 100 compared to instruments with a single counter, while maintaining comparable count statistics. Present work describes a 128-channel detector working with a standard diffractometer. The detector is 12.8 mm long and covers the angular range of 3.2 deg. We discuss the diffraction geometry in real and reciprocal space, the FWHM of diffraction peaks, and the background level. Measurements were made on standard samples and on complex samples of industrial importance (e. g., portland clinker). Applications of the detector to diffraction measurements of single crystals and thin films are discussed briefly.
Authors: Jan T. Bonarski
Abstract: Crystallographic texture is one of frequently investigated properties of near-surface regions. From the application point of view, the inheritance effect of the crystallographic orientation of a substrate is important for layered structures. The investigation of the texture of layered structures or gradient materials by means of X-ray diffraction back-reflection pole figure measurements requires a control of the information depth. Such measurements at a controlled information depth can be achieved by means of non-symmetrical diffraction geometry, employing a constant value of falling angle of the incident beam. Thus, the texture of near-surface layers with a defined thickness can be examined, as in tomographic techniques. In this work, the method of texture analysis based on a controlled information depth was applied to the investigation of the texture inheritance of a Zn protective layer on deep drawing steel. Moreover, the crystallographic relations between the texture of substrate and deposited layer, termed as texture inheritance, were considered.
Authors: M. Hecker, N. Mattern, W. Brückner, C.M. Schneider
Abstract: The subject of the present investigation is the influence of annealing on the microstructure of Co thin films. In particular, the evolution of the texture during annealing is studied and compared with that of Co/Cu multilayers of different individual layer thicknesses. 400nm thick Co films show a h.c.p. structure with a weak preference of the <001> texture component and a broad distribution of grain orientations. Annealing at about 350°C results in a strong increase of the h.c.p. <001> component, nearly complete disappearance of the statistical distribution and grain growth of a minor f.c.c. fraction in the films. In-situ XRD measurements on single Co films during annealing confirm that the texture change is irreversible. Multilayer stacks of Co/Cu layers show various texture changes depending on the individual layer thickness (ranging between 100nm and 1nm). Generally, with decreasing individual layer thickness and increasing annealing temperature the f.c.c. content in the multilayers increases at the expense of the h.c.p. fraction.

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