On High-Resolution Reciprocal-Space Mapping with a Triple-Crystal Diffractometer for High-Energy X-rays

Abstract

High-energy X-rav diffraction by means of triple-crystal techniques is a powerful tool for investigating dislocations and strain in bulk materials. Radiation with an energy typically higher than 80 keV combines the advantage of low attenuation with high resolution at large momentum transfers. The triple-crystal diffractometer at the High Energy Beamline of the European Synchrotron Radiation Facility is described. It is shown how the transverse and longitudinal resolution depend on the choice of the crystal reflection, and how the orientation of a reciprocal-lattice distortion in an investigated sample towards the resolution element of the instrument can play an important role. This effect is demonstrated on a single crystal of silicon where a layer of macro pores reveals satellites around the Bragg reflection. The resulting longitudinal distortion can be investigated using the high transverse resolution of the instrument when choosing an appropriate reflection.

High‐Energy X‐Rays: A tool for Advanced Bulk Investigations in Materials Science and Physics

“…Especially high resolution in reciprocal space is obtained with a triple-axis diffractometer and detailed descriptions, strategies for reciprocal space mapping and resolution are given in dedicated papers (Neumann, 1991;Neumann et al, 1994;Ru¨tt et al, 1995;Bouchard et al, 1998;Liss et al, 1998b;Ru¨tt et al, 2001). Investigations of lattice distortions in perfect (Liss et al, 1997a;1998a) and imperfect materials (Bouchard et al, 1993;Liß, 1994;Magerl et al, 1995;Helmers, 1996), studies of macroscopic thick or industry relevant samples (Royer and Bastie, 1997;Royer et al, FIGURE 16 (a) Experimental Debye-Scherrer rings R1-R5 obtained at 90 keV on TiAl (R1, R4, R5) and a further window materials (R2, R3) centered around M. The rings demonstrate dispersion with the nondispersive point Z as reconstructed from the data.…”

“…They have been employed by the most different techniques concerning different questions, as the Compton spectroscopy to measure the momentum-distributions of bound electrons (Isaacs et al, 1999;Suortti et al, 2001) or the atomic and nuclear spectroscopy to access high-energy levels (Bikit et al, 1987;Materna et al, 1999;Schnier, 2002). High-resolution triple crystal diffractometry is pursued to investigate phase transitions in single crystals such as magnetic or charge ordering and structural changes (Strempfer et al, 1996(Strempfer et al, , 1997Chatterji et al, 1998;Wilkins et al, 2000;Bastie et al, 2003;Hatton et al, 2003;Liss et al, 2003;Miclaus and Goorsky, 2003) or to analyze artificial superstructures or tiny strain gradients as in optical band-gap structures (Liss et al, 1998b) or ultrasonically excited crystals (Liss et al, 1997a(Liss et al, ,b, 1998a. Both white beam and monochromatic beam technologies can be employed to study residual strains and textures in polycrystalline samples for materials science purposes (Reimers et al, 1998Pyzalla et al, 1999Pyzalla et al, , 2000aPyzalla et al, ,b,c, 2001Withers et al, 2002;Brokmeier et al, 2003;Wcislak et al, 2003).…”

Probing the strain distribution within a single crystal superalloy during high temperature testing

“…The aim of the present paper is to show that the combination of in situ experiments using high resolution synchrotron X-Ray diffractometry and diffraction peak modelling can be such a tool. a Corresponding author: alain.jacques@univ-lorraine.fr Figure 1 shows the layout of a Three Crystal Diffractometer [4]. The initial polychromatic X-Ray beam first goes through a (311) silicon monochromator.…”

Diffractometer for high energy X-rays at the APS

“…At high photon energies momentum transfers of Q >45~-1 are easily achievable. In addition the correction factors due to polarization, absorption and extinction are in general small [1,2,3]. A special application is non-resonant magnetic scattering, where at high X-ray energies the magnetic cross-section is proportional to the square of the spin component perpendicular to the scattering plane [4].…”

“…diffractometers for high photon energies at the HASYLAB (Germany) and ESRF (France) [2,3], this diffractometer utilizes the vertical scattering plane to take full advantage of the small vertical divergence of the beam and to allow horizontal focusing of the broad beam from the wiggler without disturbing the resolution of the instrument. The instrument is designed to carry heavy sample equipment up to a weight of 200 kg, while maintaining high resolution and low background.…”