Elucidation of zeolite microstructure by synchrotron X-ray diffuse scattering

Diffuse scattering data from natural mordenite crystals are shown to exhibit a complex distribution of weak features which have been mapped out using a synchrotron X-ray source and a CCD detector. Comparison with computer-simulated diffuse scattering patterns yields a detailed three-dimensional columnar defect structure and reveals that roughly one third of the mordenite's columnar defects cooperate to form a block-mosaic pattern of {110} stacking faults.

Polarization switching in BaTiO₃ thin films measured by X-ray diffraction exploiting anomalous dispersion

The polarization state of BaTiO₃ thin films was switched by employing external electric fields. Using the anomalous signal of the Ba atom, the structural differences between the two polarization states were determined from X-ray diffraction experiments.

The contrast of inclusions compared with that of micropipes in back-reflection synchrotron white-beam topographs of SiC

X-ray topographic images of inclusions in SiC are described, and compared with similar images of micropipes and with computer simulations. The natures of both types of defect image are discussed.

The use of error-correcting codes for the decomposition of a powder diffraction pattern

Error-correcting codes are used to increase the efficiency of powder pattern decomposition techniques in phasing procedures.

Guidelines for the implementation of XY variable-geometry converging multichannel collimation in a specific SANS facility

The performance of SANS instruments using a combination of variable-geometry converging multichannel collimator units is discussed. Guidelines for the implementation of XY variable-geometry converging multichannel collimation are given.

Angle calculations for a z-axis/(2S+2D) hybrid diffractometer

Angle calculations are presented for a new `hybrid' diffractometer that consists of a base instrument that can be combined with two different detector arms. The inclusion of a second sample rotation stage is discussed.

Scattering from cylinders with globular end-caps

Analytical expressions for the scattering form factor and radius of gyration for a cylinder with globular end-caps are presented. The possible applications of the form factor in colloidal and biological systems are discussed.

High-throughput powder diffraction. I. A new approach to qualitative and qu­antitative powder diffraction pattern analysis using full pattern profiles

Statistical tests based on Pearson and Spearman coefficients and the Kolmogorov–Smirnov test are used to match powder diffraction patterns qualitatively using the full peak profiles. The method can be extended to quantitative analysis using least squares via singular value decomposition.

High-throughput powder diffraction. II. Applications of clustering methods and multivariate data analysis

A correlation matrix is generated to compare full profile powder patterns. This is followed by cluster analysis, multivariate data analysis and data visualization to classify the patterns into groups and thus to identify polymorphs and mixtures.

Protein crystallography with spallation neutrons: collecting and processing wavelength-resolved Laue protein data

Methods for collecting and processing wavelength-resolved Laue data at the protein crystallography station at Los Alamos Neutron Science Center have been developed.

Ab initio protein phasing: the Patterson deconvolution method in SIR2002

The Patterson deconvolution method has been implemented in the SIR2002 program, allowing the ab initio solution of protein crystal structures in a very short computing time.

Using image analysis for automated crystal positioning in a synchrotron X-ray beam for high-throughput macromolecular crystallography

A fully automated image analysis method for detecting and centring protein crystals for X-ray crystallography is described.

Periodic dislocation configuration analysis by lattice distortion evaluation: micromechanical approach and X-ray diffraction line broadening

This work concerns dislocation microstructure analysis in order to assess stored elastic energy using Fourier coefficients of diffraction lines. These coefficients are related to the lattice distortion heterogeneity evaluated using a micromechanical approach.

Automatic classification of protein crystallization images using a curve-tracking algorithm

A curve-tracking computer algorithm to classify crystallization images automatically is described.

Structure determination of diclofenac in a diclofenac-containing chitosan matrix using conventional X-ray powder diffraction data

The crystal structure of diclofenac embedded in a diclofenac-containing chitosan matrix has been determined from conventional X-ray powder diffraction data.

A time-resolved SAXS study on the crystalline morphology of long-term stored isotactic polypropylene

The crystalline morphology of a long-term stored metallocene isotactic polypropylene (mPP) is compared with that of a freshly crystallized sample. It is found that both α and γ crystal forms occur in the long-term stored mPP, whereas freshly crystallized mPP contains only the α crystal form; it is inferred that the crystal stacks of the α and γ forms in the long-term stored mPP are arranged according to the block mode.

An evaluation of methods of diffraction-line broadening analysis applied to ball-milled molybdenum

Crystallite sizes and microstrains in ball-milled molybdenum, as determined from diffraction-line broadening analysis, depend on the method of analysis. Broadening due to microstrain can be simulated with a strain field model.

A cell for the in situ study of electrocrystallization

A new cell for studying electrocrystallization in situ on a diffractometer is reported, in which the working electrode, fabricated from a propelling pencil lead encased in glass, is designed to sit in the path of the incident X-ray beam so that processes occurring at its tip can be studied using diffraction methods. Practical difficulties of both design and data collection are discussed, as well as advantages and limitations of the method.

A helium-purged beam path to improve soft and softer X-ray data quality

A helium-purged beam path implemented at the Elettra X-ray diffraction beamline is described. The advantages of its use are analysed for diffraction data collected at wavelengths in the range 1.5–2.65 Å.

Comments on Small-angle neutron scattering analysis of the precipitation behaviour in a maraging steel by Staron, Jamnig, Leitner, Ebner & Clemens (2003)

Comment on Staron, Jamnig, Leitner, Ebner & Clemens [J. Appl. Cryst. (2003>), 36, 415–419].

Imaging modulated reflections from a semi-crystalline state of profilin:actin crystals

The rotation method and fine φ-slicing have been used to visualize the modulated diffraction pattern of a semi-crystalline state of profilin:actin.

A new algorithm for performing three-dimensional searches of the Cambridge Structural Database

A new search algorithm, 3DSEARCH, is presented that can identify challenging extended chemical queries from three-dimensional crystal structure data. Timing information is presented for example searches, which demonstrate the ability of the algorithm to identify queries containing several substructures and several intermolecular connections.

CIF applications. XV. enCIFer: a program for viewing, editing and visualizing CIFs

enCIFer is an interactive program which permits files in CIF format to be viewed, and syntax errors to be located and corrected for both individual and looped data items. The software also allows new data to be incorporated and the structure(s) contained in a small-molecule CIF to be visualized and manipulated.

Hot pressing of germanium monochromator crystals

Hot pressing of germanium (311) single crystal at 1073 K at a pressure of 10.7 MPa gives typical mosaic widths of 0.5° in one direction and 0.2° in the other.

Mesoscopic crystallography of shear-aligned soft materials

The development of a novel device for examining the three-dimensional structure of shear-aligned soft materials using small-angle X-ray scattering is reported.

A new method of cleaning X-ray tubes from solid carbonates

A new fast chemical method for cleaning X-ray tubes from deposited carbonates, based on the high affinity of citric acid toward calcium and magnesium, is presented.

VRML general position diagrams of the magnetic subperiodic groups

Three-dimensional general position diagrams of all magnetic subperiodic groups have been developed. Each diagram can be rotated and zoomed to aid in the visualization of the general position diagram and includes both the general positions of the atoms and the general orientations of the associated magnetic moments.

XDSi: a graphical interface for the data processing program XDS

A Tcl/Tk graphical user interface has been developed for the X-ray diffraction data processing package XDS. The interface simplifies routine tasks, such as input file retrieval and editing, examination of the output and file format conversion.

Erwin Félix Lewy-Bertaut (1913–2003)

Félix Bertaut, space groups and the International Tables for Crystallography

Sivaraj Ramaseshan (1923–2003)

Crystal growth for beginners

Forthcoming meetings and short courses