Journal of Applied Crystallography最新文献

Ammonium dihydrogen phosphate (ADP) crystals of large dimensions (80 × 80 × 20 mm), to be used as X-ray beam expanders in the BEaTriX facility at INAF-OABrera, have been characterized on the ESRF BM05 beamline using the rocking curve imaging technique to test the planarity of the lattice planes. The difference in Bragg angles between the Si(111) monochromator and ADP(008) strongly affects the angular position of the diffraction peak as a function of sample position due to wavelength dispersion, which must be corrected in order to measure lattice curvature accurately. It is found that the diffracted image size exhibits a 4.5% elongation parallel to the scattering plane, an effect which has not been previously accounted for and which may lead to an incorrect wavelength dispersion correction. This contribution is critical for accurate measurement of resolution and lattice plane curvatures.

X-ray diffraction pole-figure measurements are essential to analyze crystallographic texture in thin films and nanoparticles. Conventionally, large and equal incident and exit angles beyond the critical angle of the studied material are used, limiting surface sensitivity. This study demonstrates the use of grazing-incidence wide-angle X-ray scattering (GIWAXS) while rotating the sample azimuthally in its own plane to acquire pole figures that are more sensitive to the near-surface region compared with pole figures measured in standard Schulz geometry. Comparative measurements on supported Pt nanoparticles in GIWAXS and Schulz geometry at two different synchrotron beamlines confirm the improved sensitivity of the GIWAXS pole figures. By tuning the incident angle, the substrate diffraction background can be reduced and the information depth inside a Pt thin film can be selected. In addition, the near-horizontal sample orientation during GIWAXS – only tilted by the small incident angle – reduces constraints on sample environments compared with conventional Schulz geometry. The increased sensitivity to the near-surface region of a grazing-incidence X-ray beam, combined with the simpler measurement geometry, prove grazing-incidence pole figures to be powerful for future in situ and ex situ texture analysis on thin films and supported nanoparticles.

An X-ray Kirkpatrick–Baez nanofocusing system based on total-reflection mirrors has been developed at the hard X-ray nanoprobe beamline of the Shanghai Synchrotron Radiation Facility. Here, we provide an overview of the beamline and discuss the features of the Kirkpatrick–Baez total-reflection focusing system. Through the integration of speckle scanning metrology and the knife-edge scanning technique, the system underwent rigorous testing and alignment to achieve an optimized configuration. The reconstructed focusing spot size was 61 nm (H) × 55 nm (V) at an energy of 10 keV, which is close to the theoretical value. To ascertain the spot size and beam application, two-dimensional X-ray fluorescence imaging and ptychography imaging were used. The results showed that the spatial resolution was better than 58 nm in the horizontal direction and 42 nm in the vertical direction for the fluorescence test and 50 nm for the ptychography test. The imaging outcomes underscore the system's robustness and its capacity for high-resolution experimental applications.

The scattering factors of the Ca, P, O and H atoms in hydroxyapatite crystals are refined against theoretical structure factors derived from the electron density distribution optimized using density functional theory. A methodology is proposed to avoid artifacts arising in the density map grid from sharp density peaks. Significant improvements in the accuracy of the structural geometry, atom site occupancies and anisotropic displacement parameters provided by the optimized scattering factors is demonstrated by comparing powder X-ray diffraction refinements using the derivative difference minimization method with single-crystal neutron diffraction data.

Inelastic neutron scattering (INS) experiments utilizing modern time-of-flight spectrometers enable the comprehensive mapping of the energy (E)- and momentum (Q)-resolved dynamical structure factor of single crystals, probing both the lattice and magnetic excitations. Yet, the large size and complexity of four-dimensional INS data are challenging current analysis workflows, often resulting in an underutilization of the measured information. To help address this issue, this paper introduces new software interfaced with the Mantid framework, pathSQE, designed to streamline the processing, analysis and interpretation of 4D single-crystal INS data. By automating key tasks such as 1D/2D slicing, symmetrization, Brillouin zone folding, data visualization, prioritization and filtering, and comparisons with simulations, pathSQE facilitates and accelerates INS data analysis workflows. This paper outlines the features and implementation and provides several illustrations of the use of pathSQE on data collected on single crystals using direct-geometry time-of-flight spectrometers at the Spallation Neutron Source, including Ge, FeSi, MnO and SnS single-crystal measurements on the ARCS, HYSPEC and CNCS neutron spectrometers. Beyond streamlining post-experiment data processing, pathSQE establishes an automated and modular processing pipeline that could support future real-time experiment steering.