A new method for analysing peak broadening caused by compositional fluctuation in X-ray diffraction measurements

A new method for analysing X-ray peak broadening caused by compositional fluctuation is proposed. The method is useful for simple identification of X-ray peak broadening caused by compositional fluctuation for samples with various types of epitaxial layers.

Robust Rietveld refinement in the presence of impurity phases

A modified least-squares analysis is presented that allows reliable structural parameters to be extracted from a powder diffraction pattern even in the presence of a substantial unmodelled impurity contribution. The algorithm is developed within the context of Bayesian probability theory.

Planar faults in layered Bi-containing perovskites studied by X-ray diffraction line profile analysis

Profile fitting procedures associated with integral breadth studies and Fourier analysis are applied to the study of the complex Bi-containing layered perovskite SrBi₂Nb₂O₉. Strong anisotropic line broadening is observed.

A random procedure for the decomposition of a powder pattern in EXPO

A new full-pattern decomposition procedure for powder data is described, aiming at improving the phasing process.

Salts of aromatic carboxylates: the crystal structures of nickel(II) and cobalt(II) 2,6-naphthalenedi­carboxylate tetrahydrate

The crystal structures of the isostructural [Ni(C₁₂H₆O₄)(H₂O)₄] and [Co(C₁₂H₆O₄)(H₂O)₄] have been determined using Monte Carlo simulated annealing techniques and laboratory X-ray powder diffraction data. The water-molecule hydrogen atoms were located by quantum chemical geometry optimization; molecular mechanics energy minimizations suggest that coordination and hydrogen-bonding interactions are most important in determining the crystal packing.

Measurement of subtle strain modifications in heterostructures by using X-ray mapping in reciprocal space

The application of X-ray mapping in reciprocal space to the measurement of the subtle strain modifications in epitaxically grown structures as well as in implanted structures with unknown lattice mismatches is analysed. Special attention is paid to the reasons for the enhanced precision of this technique as compared with the diffraction profile measurements.

Orthorhombic lattice deformation of CuAlBe shape-memory single crystals under cyclic strain

X-ray diffraction experiments were carried out to prove that X-ray methods can be used to assess strain-induced fatigue in CuAlBe shape-memory alloys.

Direct determination of microstructural parameters from the X-ray diffraction profile of a crystal with stacking faults

The practical aspects of a recently deduced formalism for the direct solution of the powder diffraction pattern of a layer crystal are addressed. The solution when combined with a deconvolution procedure based on a series development can yield the correlation function between laterally displaced layers.

The precision of diffraction peak location

A simple expression is presented for estimating the precision of diffraction peak location that can be achieved for a Gaussian diffraction peak with a flat background, in terms of the standard deviation, integrated intensity and peak height to background ratio. The efficacy of the expression is confirmed by simulation and by application to neutron diffraction peak profiles obtained at many facilities worldwide as part of a residual-strain determination round robin study.

Tracking: a method for structural characterization of grains in powders or polycrystals

A method is presented for fast and non-destructive characterization of individual grains inside bulk materials with respect to position, volume and orientation.

Three-dimensional maps of grain boundaries and the stress state of individual grains in polycrystals and powders

Based on the tracking concept, a fast and non-destructive method for mapping the grain boundaries of a polycrystal in three dimensions is demonstrated. Furthermore, methods for characterizing the stress state of the individual embedded grains are presented.

Rietveld refinements on laboratory energy dispersive X-ray diffraction (EDXD) data

Rietveld refinements on energy dispersive X-ray data are reported.

Controllable variation of the intensity of diffracted X-ray beams and double modulation of such beams for transmission and reception of audio information

This paper discusses research devoted to the study of the intensity change of diffracted and transmitted X-ray beams under the action of a temperature gradient or acoustic oscillations, as well as the techniques for `controllable complete reflection' of transmitted X-radiation in the direction of the diffracted beam.

Teaching diffraction using computer simulations over the Internet

An interactive teaching tutorial on diffraction, using computer simulations, is presented. Interaction with the simulation program is performed via an interface that can be accessed with any Internet browser.

Scattering curve and radius of gyration of a straight chain of identical spheres

The scattering intensity of a straight chain of N identical spheres and its radius of gyration are reported.

Using Situs for the registration of protein structures with low-resolution bead models from X-ray solution scattering

Documentation of the Situs package and demonstration of its use in visualization and mutual registration of atomic structures and low-resolution bead models from X-ray solution scattering are presented.

NADA – a computer program for the simultaneous refinement of orientation matrix and modulation vector(s)

The computer program NADA refines simultaneously the orientation matrix and the components of up to three modulation vectors by the least-squares method.

MCGRtof: Monte Carlo G(r) with resolution corrections for time-of-flight neutron diffractometers

The MCGR program of Pusztai & McGreevy has been modified to account for the experimental resolution of time-of-flight neutron diffractometers.

PSEUDO: a program for a pseudo­symmetry search

The program PSEUDO performs a pseudosymmetry search among the supergroups of the space group of a given structure.

xd_red-1.0: synchrotron and in-house X-ray diffraction data reduction and analysis program

A program system to analyse, correct and merge single-crystal synchrotron or in-house X-ray diffraction data is described.

Iterative unfolding of two-dimensional data by Siska's method

A Fortran program, SM, for unfolding two-dimensional data by Siska's method is described.

Determination of γ′ solution temperature in Re-rich Ni-base superalloy by small-angle neutron scattering. Erratum

Erratum to J. Appl. Cryst. (2001), 34, 541–548.

From molecules to crystallizers. An introduction to crystallization.

The crystal lattice: phonons, solitons, dislocations

New analytical software for XRD simplifies identification of complex phase mixtures

New X-ray Hystar range of high-performance image detectors

New 9308-PCI picosecond time analyzer with PCI-bus interface

Forthcoming meetings and short courses