Energy-dispersive Laue experiments with X-ray tube and PILATUS detector: precise determination of lattice constants

Abstract

A PILATUS detector in combination with a conventional sealed X-ray tube was used for the development of the energy-dispersive Laue diffraction technique, which can be applied for precise measurements of single-crystal lattice constants in transmission and reflection modes without moving the sample. Exploiting the ability of PILATUS detectors to suppress counting of X-ray photons below a certain energy threshold allows one to recover the wavelength of diffracted Bragg reflections, reconstruct the three-dimensional reciprocal-space pattern, index X-ray diffraction peaks, and find the orientation and lattice parameters of the crystal without any a priori information about the sample. By making some geometrical assumptions and using a set of fast in situ calibration procedures, it is possible to simultaneously refine lattice constants and hardware correction factors, which simplifies the sample preparation and measurement strategies. Several samples [silicon, quartz, fluorite (CaF 2 ), o 0 -Al 13 Co 4 quasicrystal approximant, Laves (MgZn 2 ) and Bergman (Mg 32 (Al,Zn) 49 ) phases] were studied with the developed technique, and 0.01 Å and 0.1 precisions were routinely reached for lattice vector lengths and angles, respectively. The use of the developed methods is only limited by the energy resolution of the PILATUS detector, where lattice vectors with >27 Å length cannot be reliably resolved.

Materials Separation via the Matrix Method Employing Energy-Discriminating X-ray Detection

“…Detectors capable of full energy resolution imaging with a limited degree of pixelation first became commercially available well over a decade ago, however, the limited number of pixels and large pitch currently associated with these types of detectors [34] limits their application to highresolution X-ray µCT. A large number of different types of energy-discriminating detector are now commercially available and could potentially be used with the matrix method presented here, including the Medipix [35], Pilatus [36], XPAD [37], PiXirad [15], HEXITEC detector [38] and more recently, the hyperspectral X-ray detector [39]. Hyperspectral X-ray detectors are able to provide a full X-ray spectrum at each individual detector pixel, typically by separating and classifying the incident X-ray photon energy into a very large number (up to several thousand) of discrete energy bins.…”

A laboratory transmission diffraction Laue setup to evaluate single-crystal quality

“…For instance, polychromatic diffraction contrast tomography experiments can also be performed under laboratory conditions (King et al, 2014;Bachmann et al, 2019). Recently, a new technique called energy-dispersive Laue diffraction (EDLD) has been developed to determine the lattice parameters of an unknown crystal using synchrotron (Shokr et al, 2019) and laboratory (Kurdzesau, 2019) radiation. EDLD uses the latest generations of X-ray detectors such as pnCCD (Leitenberger et al, 2008) or hybrid photon counting (HPC) detectors (Brö nni-mann et al, 2001) to measure the energy of the diffraction spots.…”