February 2012 issue
A combination of self-consistent and geometric mean algorithms is applied to describe the pressure-dependent anisotropic elastic properties of a textured reactor graphite sample. The experimental sound velocities can reasonably be explained by a system of differently oriented extremely anisotropic flat grains, flat micropores (cracks) and spherical macropores with comparable volume fractions in the porous (∼20%) sample.
High-brilliance synchrotron radiation was used to indentify an unexpected DyH2 precipitate in Mg–20 wt% Dy alloy. This precipitate can be formed at room temperature, and its formation mechanism was further clarified.
An ellipsoidal formula for the correction of anisotropic broadening in X-ray powder diffraction on samples with nanosized crystals has been applied. Information about crystallite shapes and sizes provided by the method is verified by imaging techniques.
The formation of rutile passivation layers on Magnéli-phase anodes in an operational titanium electrowinning cell was observed by energy-dispersive X-ray diffraction. Quantitative phase analysis of the energy-dispersive data was undertaken using a crystal-structure-based Rietveld refinement and layer thicknesses were calculated.
Corrections and image processing algorithms for data analysis with a prototype hybrid pixel detector are reported in the context of three different X-ray diffraction experiments with synchrotron radiation.
Two high-pressure X-ray diffraction studies were conducted on the important oxidizer potassium chlorate (KClO3) at 300 K. In the first study, the radiation-induced decomposition rate was observed to significantly diminish with pressure as the sample transformed from the monoclinic to the high-pressure rhombohedral phase, suggesting a phase-dependent decomposition rate, and in the second study, the equation of state was determined up to 14.3 GPa.
A new crystallization system is described, which makes it possible to use an evaporation-based microfluidic crystallization technique for protein crystallization. Using this method, crystal growth could be improved so that approximately 1 mm-sized lysozyme crystals were obtained more successfully than using standard methods.
The method and software of extended convolutional multiple whole profile (eCMWP) line profile analysis is used to determine the substructure in different texture components in terms of dislocation densities, subgrain size and twin boundary densities in nanocrystalline Ni thin films with different fiber textures. The diffraction patterns are measured in a high-angular-resolution X-ray diffractometer with almost parallel beam geometry, where the specimens are stationarily oriented for the hkl peaks corresponding to the different texture components.
GeSi nanoparticles were characterized by grazing-incidence small-angle X-ray scattering, X-ray diffraction and extended X-ray absorption fine structure spectroscopy. Besides direct measurements, important indirect results only accessible by combining the results of the various techniques have been obtained.
A characterization of the X-ray beam generated from differently sized two-dimensional waveguides was performed, giving values for the beam geometry, the transmission efficiency and absolute fluxes. A first high-resolution nanodiffraction experiment using the beam out of a two-dimensionally confining waveguide was performed on a nanocrystalline TiN hard coating in order to reveal the local gradients across the blasted coating.
A method and software to calculate the absorption factor for the infinite-cylinder transmission Debye–Scherrer geometry with two-dimensional area powder pattern registration are presented.
Multiple reflection effects in perfect crystals can be strongly enhanced by elastic bending. They can be used for high-resolution monochromatization.
Combined refinements of local atomic structure that involve simultaneous fitting of powder-averaged and single-crystal data were implemented as an extension to the publicly available RMCProfile software. The procedure was tested using simulated data generated for a realistic model of perovskite-like KNbO3, which exhibits strongly correlated Nb and O displacements.
Lattice strain was determined by neutron transmission and diffraction during tensile testing. The position dependence of the lattice strain was clearly observed by Bragg-edge transmission.
Anomalous dispersion at the Si K edge is used to control the refractive index of an Si substrate to match that of a polymer thin film on its surface. Diffuse scattering from the film/substrate interface disappears at a photon energy very close to the Si absorption edge.
A method is derived to calculate the attenuation correction factors for elastic or inelastic X-ray or neutron scattering experiments using a spherical sample that is fully or partially illuminated by an incident beam of rectangular cross-sectional area.
The resolution calculated for a Debye–Scherrer ring that includes the effect of gravity is compared with results from measurements taken on a sample of opal.
A curated online protein block sequence database, PDB-2-PB, with user-friendly sequence retrieval systems has been developed. The options available in PDB-2-PB are used to extract the protein block sequence of a chain along with its corresponding chain information and amino acid sequence.
A computer program is reported for plotting stereographic projection and exploring crystallographic orientation relationships. It offers a user-friendly interface to fully control stereographic projections of an arbitrary pole centre for an arbitrary crystal structure and to illustrate composite stereographic projections.
A low-cost automatic sample changer for powder or polycrystalline samples is here described. The sample changer was designed so that it can be fitted into a Bruker SMART APEX X-ray single-crystal diffractometer, but it can be easily adapted to diffractometers from other makers.
A prototype jig to attach a protein crystallization plate to a standard X-ray goniometer has been designed and constructed. This allows a low-cost implementation of in situ diffraction using the available home-laboratory X-ray source.
addenda and errata
Errors in the paper by Liu, Waclawik & Luo [J. Appl. Cryst. (2010), 43, 448–454] are corrected.