The structure factor in small-angle scattering and the effect of deviation from spherical symmetry

Spherical symmetry is a frequent assumption when the structure factor is used for data analysis of small-angle scattering data. The present article suggests a correction which may be used for non-spherical scatterers at low volume fractions.

Towards three-dimensional qu­antitative reconstruction of cement microstructure by X-ray diffraction microtomography

A post-processing method for X-ray diffraction computed microtomography analysis of complex materials is presented. The paper shows the potential of the method in constructing three-dimensional quantitative maps of the individual solid phases present in hydrating cement pastes.

Measuring the linearity of X-ray detectors: consequences for absolute attenuation, scattering and absolute Bragg intensities

How to test and verify the required linearity of X-ray detectors is discussed for a wide range of crystallographic and X-ray measurements.

Real-time synchrotron powder X-ray diffraction study of the antisite defect formation during sub- and supercritical synthesis of LiFePO₄ and LiFe_1−xMn_xPO₄ nanoparticles

In situ synchrotron powder X-ray diffraction is used to study the formation of LiFePO₄ and Li(Fe_1−xMn_x)PO₄ (x = 0.25, 0.50 and 0.75). This technique can be used to follow the influence of time, temperature and manganese doping on the Li–Fe antisite defect concentration, and it is shown that even under supercritical conditions a reaction time of several minutes is required to suppress the defects.

The ABC of powder diffractometer detector coverage

It is shown in a general optimization that for a reactor-based constant-wavelength neutron source a diffractometer should not have a large detector solid angle for the best performance.

Precision of lattice strain and orientation measurements using high-energy monochromatic X-ray diffraction

A systematic framework for estimating the uncertainty associated with monochromatic X-ray diffraction-based measurements of the stretch and orientation of a crystalline lattice, using a single full rotation scan, is presented. This framework is validated using a ruby single crystal, and an example application of the technique to a heavily deformed titanium alloy grain embedded in a polycrystal is described.

Study of the influence of dopants on the crystalline perfection of ferroelectric glycine phosphite single crystals using high-resolution X-ray diffraction analysis

Good quality single crystals of pure and doped glycine phosphate were grown by both solvent-evaporation and temperature-cooling techniques. High-resolution X-ray diffraction results confirm the crystalline perfection of the grown crystals.

Thermal structural properties of calcium tungstate

The results of in situ temperature-resolved powder diffraction studies confirm the scheelite type of structure for calcium tungstate over a broad temperature range of 5–1773 K. The layered structure formed by two-dimensional CsCl-type arrangements of Ca cations and WO₄ complexes is shown to be the primary reason for the observed anisotropy of thermal expansion in calcium tungstate.

Building and refining complete nanoparticle structures with total scattering data

The use of two programs, DISCUS and DIFFEV, is described and demonstrated for the application of total scattering data to the structure refinement of complete nanoparticle systems.

Comprehensive upgrade of the high-resolution small-angle neutron scattering instrument KWS-3 at FRM II

An essential upgrade of the neutron optics of KWS-3 has been performed. Conceptual improvements, such as the extension of the Q range by one order of magnitude and calibration of the scattering curves by the direct-beam method, give access to important structural and quantitative parameters of large-scale structures.

On the validity of simple precipitate size measurements by small-angle scattering in metallic systems

Simple evaluation models for particle size and particle size distribution from small-angle scattering are assessed within the framework of large data sets obtained by time-resolved or scanning experiments on metallic systems.

X-ray diffracted intensity for double-reflection channel-cut Ge monochromators at extremely asymmetric diffraction conditions

The X-ray diffracted intensity, Bragg peak width and angular deviation due to refraction have been measured in a channel-cut Ge crystal at angles of incidence near the critical angle. The double-diffracted intensity is very high even near the critical angle. The unexpected broadening of the Bragg peak near the critical angle and the contrast seen in the topographic image of the diffracted beam could be explained by an imperfect surface planarity of the crystal.

Off-specular data representations in neutron reflectivity

The different methods of data acquisition and representation of off-specular neutron reflectometry measurements are discussed. This is illustrated by diffuse scattering data measured on neutron waveguides on both fixed-wavelength and time-of-flight spectrometers.

Debye–Scherrer rings from block copolymer films with powder-like order

The distortion of Debye–Scherrer rings from powder-like lamellar domains in thin diblock copolymer films due to refraction at grazing angles is discussed within the distorted-wave Born approximation.

Near-surface relaxation structure of annealed block copolymer film on Si substrates examined by grazing-incidence small-angle scattering utilizing soft X-rays

Using grazing-incidence small-angle scattering profiles of an annealed SEBS8 triblock copolymer measured at 1.77 keV, surface-sensitive nanostructure analysis of microphase-separated lattice structures has been demonstrated. The lattice is composed of spherical cores, which are elongated in the out-of-plane direction by 25% within 50 nm from the surface.

Application of synchrotron-based reciprocal-space mapping at a fixed angular position to identification of crystal symmetry of Bi₄Ti₃O₁₂ epitaxial thin films

Synchrotron-based reciprocal-space mapping at a fixed angular position was applied to 50 nm-thick and 3 nm-thick Bi₄Ti₃O₁₂ films that were epitaxically grown on TiO₂ (101) substrates. The crystal structures of the films were determined to be monoclinic with a space group of B1a1 or a lower crystal symmetry.

CYCLOPS – a reciprocal-space explorer based on CCD neutron detectors

The new single-crystal neutron Laue diffractometer CYCLOPS at the Institut Laue–Langevin combines a large solid angle of detection with the fast readout of CCD detectors to offer a unique instrument for real-time exploration of reciprocal space and rapid data collection through phase transitions.

Deduction of the single-myosin-filament transforms from partially sampled layer lines in the X-ray diffraction pattern from vertebrate striated muscle

The single-myosin-filament transform from lattice-sampled layer lines in the X-ray diffraction pattern from vertebrate striated muscle was deduced by the cylindrically averaged difference Patterson function.

X-ray strain analysis of {111} fiber-textured thin films independent of grain-interaction models

Elastic anisotropy of thin polycrystalline films is difficult and time consuming to approach experimentally and theoretically with available scale transition models. This article proposes an original physical analysis of synchrotron X-ray diffraction data obtained under two particular geometries for {111} fiber texture; this approach allows the accurate determination of single-crystal elastic compliances of thin films.

Three-dimensional spatially resolved neutron diffraction from a disordered vortex lattice

A novel slicing neutron diffraction technique using atypical collimation and an areal detector is reported. It allows for observing the three-dimensional disorder of the vortex matter inside an as-grown Nb single crystal.

CrystalPlan: an experiment-planning tool for crystallography

This paper describes CrystalPlan, a software program for the automatic creation of crystallography experiment plans for time-of-flight diffractometers.

Abstractions, algorithms and data structures for structural bioinformatics in PyCogent

Flexible abstractions, algorithms and data structures for protein structure analysis have been developed and integrated into the PyCogent bioinformatics software, thereby extending the scope of this sequence-based toolkit to enable combined sequence/structure-based bioinformatic studies.

A flow-through reaction cell that couples time-resolved X-ray diffraction with stable isotope analysis

A design for a non-metallic flow-through sample cell is described. It is useful for combining powder X-ray diffraction with aqueous analysis of mineral–fluid reactions.

Tri­methylamine N-oxide as a versatile cryoprotective agent in macromolecular crystallography

Trimethylamine N-oxide has been applied successfully for cryoprotecting various macromolecular crystals.

Forthcoming meetings and short courses