April 2012 issue
Depth-resolved microbeam diffraction was used to measure diffraction line profiles from numerous individual dislocation cell walls and cell interiors in a heavily deformed Cu single crystal, allowing the construction of the cell-interior and cell-wall subprofiles that have been approximated in the line profile analysis literature for the past 30 years. Comparison of the reconstructed subprofiles and the macroscopic asymmetric line profile from the same sample allows the first direct tests of many of the assumptions that have been used in such analyses.
A versatile flow-through reaction cell, featuring independent and accurate controls of temperature (up to 673 K), pressure (up to 46 MPa), fluid volume (≥65 ml) and flow rate (0.01–10 ml min−1), has been developed and commissioned for in situ neutron diffraction investigation of crystallization under mild to extreme hydrothermal conditions (e.g. supercritical).
This paper outlines a data collection strategy and the necessary corrections for synchrotron powder data collected in flat-plate geometry. A number of solid solutions in multiferroic Ga(2−x)FexO3 have been used to deliver very accurate crystal structures suitable for modelling material functionality.
The morphology, structure and luminescence properties of one-dimensional vertically aligned Sb-doped ZnO nanowires on a silicon substrate have been studied. The results show that the use of Si(111) is a critical factor for the growth of vertically aligned nanowires.
The relative stability of high-pressure phases of NiSi has been determined by ab initio calculations. Above ∼250 GPa, NiSi adopts the CsCl structure and therefore at the pressures of the Earth's inner core it will be isostructural with FeSi.
A model is proposed to calculate the diffraction elastic constants that convert lattice strain into macroscopic stress.
The Gibbs free energy relationship between bulk (tetragonal structure) and spherulitic crystals of hen egg white lysozyme was controlled under application of an external alternating current electric field. The distribution of phases differed depending on differences in the magnitude of the electrostatic energy contribution to the respective chemical potentials of the two solid phases.
A high-throughput biological small-angle X-ray scattering facility is described, which combines single-channel robotic pipetting with a capillary-based sample cell. The design parameters, sample rinsing protocol and effects of fluid dynamics on radiation damage are examined.
The origin of the multiple orientation relationship found in the Mg/γ-Mg17Al12 precipitation system has been rationally interpreted by a simplified invariant line analysis with consideration of the pseudo-twinning relationship between close-packed planes (), (11), (033), (411) and () in the precipitate phase γ-Mg12Al17.
Using nanowire-resolved X-ray diffraction with a focused synchrotron beam, the structural composition, phase arrangement and residual strain of individual GaAs nanowires grown on Si(111) have been investigated.
A formalism is presented which allows the quantitative evaluation of grazing-incidence small-angle neutron scattering patterns from randomly oriented one-dimensional paracrystal domains with lamellar structure.
From the principles of X-ray dispersion in asymmetric Bragg reflections, typical dispersive multiple-crystal monochromators are analyzed to show that they may produce millimetre-sized virtual sources. Possible schemes to mitigate this problem for microfocusing are proposed.
This paper presents a new protocol for the in situ investigation of differential stress, principal stress direction and lattice preferred orientation in low-symmetry materials deformed at high pressure and high temperature. The method has been successfully applied to data collected on the D-DIA deformation press at the X17B2 beamline of the National Synchrotron Light Source.
Using X-ray diffraction, the high purity and high crystalline quality of millimetre-sized GeO2-based crystals obtained using the flux method have been revealed. The effect of Ge replacement by Si on the distortion of the α-quartz-type GeO2 structure was assessed by following the evolution of the intra-tetrahedral angle and other structural parameters.
The problem of light propagation in optically active anisotropic crystals is studied with a unified theory of electromagnetic plane waves transmitted in a layered homogeneous bianisotropic system. The combined analytical and experimental methods described are applicable to the determination of the spectroscopic optical activity tensor of crystals.
A new technique is introduced to remove non-sample scattering from integrated reflection intensities by utilizing changes in relative scattering vectors. This approach is found to improve data quality.
Improvements have been made to the nonlinear least-squares algorithms of the powder diffraction analysis program Z-Rietveld so that it can deal with singular matrices and intensity non-negativity constraints. Owing to these improvements, Z-Rietveld successfully executes the Pawley method without requiring any constraints on the integrated intensities, even in the case of severely or exactly overlapping peaks.
New methods have been developed for locating phosphate groups and nucleic acid bases in the electron density of RNA structures. A program, RSR, has been created for the constrained refinement of molecular fragments in model-building methods based on a phased rotation–conformation–translation function, and the programs NUT, HEL and DHL have been upgraded and organized into a program system.
An automatic system for the aggregation, semantification and presentation of open crystallographic data is presented.
Nika is a free open-source Igor Pro-based program for reduction of two-dimensional scattering data from area-detector small- and wide-angle scattering instruments to one-dimensional lineouts. It can be used in transmission and grazing-incidence geometries.
This paper introduces a new program for analyzing 57Fe conventional and synchrotron energy-domain Mössbauer spectra.
The proposed web server is an updated version of a previously developed search engine and is useful for identifying structurally similar peptide fragments.
A new suite of software is described, for processing data acquired from many small crystals illuminated `serially' by an X-ray free-electron laser.
The paper presents new developments and amendments to the ATSAS package (version 2.4) for processing and analysis of isotropic small-angle scattering data.
A new statistical method for the automatic determination of the extinction symbol from electron diffraction data is described.
The main features of the program SIR2011 are described.
A fibre-based crystal mounting technique for protein cryocrystallography has been developed.
A setup for grazing-incidence in-plane X-ray diffraction using standard laboratory equipment and its application for organic thin-film and monolayer characterization is described.