October 2011 issue
The hydration of alite is examined from a crystallographic point of view. Rietveld analysis of water/alite pastes was carried out, combined with external-standard quantification, and the measured and calculated heat of hydration results are compared.
Modified partial or no known crystal structure models have been developed to quantify turbostratically disordered nontronite in laterite ores.
Particle statistics in synchrotron powder diffractometry measured in a capillary transmission mode have been theoretically and experimentally investigated. It is shown that the size distribution of crystallites of about several micrometres can be evaluated by applying a spinner-scan method.
A new methodology is proposed for structure refinement using powder diffraction data, from which models for particle statistics and any other statistical errors can formally be optimized. Structure parameters optimized by the method tend to become closer to those obtained by a single-crystal method as compared with results from the Rietveld method.
The texture (lattice preferred orientation) of the crystallites in cortical bone samples has been studied by means of synchrotron hard X-ray diffraction, performing a combined analysis with the Rietveld method to quantify fully the preferred orientation features and to obtain lattice and microstructural parameters (such as crystallite size) simultaneously.
The evolution of γ′ morphology in SCA425 Ni-base superalloy, pre-deformed in compression, was examined by in situ small-angle neutron scattering at high temperatures. Only severe pre-straining (2%) performed at elevated temperatures causes rafting during the subsequent heating.
A numerical procedure to carry out the integral on the powder diffraction sphere in reciprocal space and obtain accurate powder diffraction peak profiles for small crystallites is presented.
Rietveld refinement of X-ray diffraction data and dilatometry performed as a function of annealing time for L-asparagine monohydrate confirmed that the phase transition associated with loss of the water molecule (anhydrous phase) is time dependent.
Two alternative theories that describe neutron scattering from periodic nanostructures are compared with each other and with experimental data. Dynamical scattering theory agrees with experiment for all scattering geometries, while the simpler phase-object approximation can only be used reliably under certain conditions.
In situ neutron diffraction during tensile tests and elastoplastic self-consistent modelling were used to study elastoplastic deformation of both phases in duplex stainless steel. By using an original calibration of diffraction data, the range of the study was extended to large sample deformation, and mechanical effects attributed to damage processes initiated in ferrite were observed.
It is shown how atomic structural information can be obtained from molecular films without further knowledge of the single-crystal structure. C60 fullerene was chosen as a representative test material.
The influence of annealing on crystal growth and the micro- and mesoscopic structures of Mn-substituted nanocrystalline zinc oxide have been investigated using X-ray diffraction, high-resolution transmission electron microscopy and small-angle neutron scattering. Attempts have also been made to establish a structure–property correlation by showing the variation of optical band gap estimated from UV–visible absorption spectra with particle size.
The thermoelastic properties and crystal structure of post-perovskite-structured CaPtO3 have been determined at pressures up to 9.3 GPa (at room temperature) and at temperatures between 2 and 869 K (at atmospheric pressure) by neutron powder diffraction. The behaviour of the cell parameters and crystal structure on compression and on thermal expansion are compared with those observed in the post-perovskite phases of MgSiO3 and CaIrO3.
Absolute structure determination features available in the crystallographic refinement program CRYSTALS are documented along with the some analysis of results obtained.
Application of a charge-flipping algorithm to two-dimensional subsets of reflection intensities derived from powder diffraction data produces phases as reliable as those obtained from high-resolution transmission electron microscopy images. These can then be used to facilitate the solution of the crystal structures of polycrystalline materials.
Modification of the preferred martensitic variant distribution by introducing a high magnetic field during the annealing process of the Ni53Mn25Ga22 ferromagnetic shape memory alloy was investigated. It is revealed that high magnetic field annealing enhances the regular arrangement of the martensitic variants from the morphological point of view and effectively modifies the preferred orientation distribution of martensitic variants without changing the misorientation between them from the crystallographic point of view.
An alternative wavelength-dispersive neutron transmission technique is applied on different instruments to investigate crystallographic preferred orientations. The validity of the results is supported by both conventional diffraction measurements and Monte Carlo simulations.
High-energy X-ray powder diffraction data, suitable for Rietveld analysis, were collected from samples in a high-pressure sample environment using a highly attenuating collimator and beam-stop assembly (background-reducing internal mask, BRIM) placed within the pressure vessel, around the sample, to block Bragg scattering from the upstream vessel wall and prevent the beam from hitting the downstream wall.
A study of the effect of Cr3+ doping in zinc tris(thiourea)sulfate (ZTS) crystals on crystalline perfection was carried out by high-resolution X-ray diffractometry. The formation of vacancies was revealed, and this was confirmed by photoluminescence studies. The optical band gap and linear refractive index of ZTS were found to increase as a result of doping.
Quantitative texture measurements were made on differently prepared α-alumina and Ti3AlC2 ceramics using a neutron diffraction area detector and an improved data-reduction algorithm. The measured textures were used to extract one-dimensional pole densities, useful in the computation of diffraction elastic constants from single-crystal constants, and these were compared with the March and Rietveld functions widely used in powder diffraction.
A new method of combined synchrotron X-ray diffraction and digital image correlation techniques has been successfully applied for accurate strain measurements of nanocomposite thin films on Kapton during biaxial tensile tests.
An investigation of the effect of Li+ and Ta5+ on the crystal structure and electrical properties of (KxNa1−x)NbO3 ceramics shows that the presence of Li+ suppresses the orthorhombic–rhombohedral phase transition at low temperatures. Phase coexistence over a wide temperature range may help to explain why the piezoelectric properties are enhanced in doped (KxNa1−x)NbO3 ceramics compared to the undoped samples.
A fully automated microfluidic sample-preparation system for protein structure analysis is presented, characterized and used to screen the structural space of an adaptor protein, identifying a reversible oligomerization relevant for the understanding of cell signalling.
An analytical description is presented of the generalized optical response for non-absorbing crystals of point-group symmetry under the influence of an externally applied electric field. Configurations of light propagation and applied electric field directions that try to decouple the contribution of the observed effects are identified.
A UMoAl multi-phase particle has been investigated by scanning X-ray diffraction computed tomography, revealing a micrometre-scale layered embedded structure morphology that is accessible neither via classical two-dimensional X-ray diffraction mapping nor by electron microscopy.
The EQ-SANS instrument has completed its construction and commission and is ready to serve users. Initial experiments show that the instrument has met its design goals.
The small-angle X-ray scattering contrast variation technique is able to suppress the air/grain interface scattering and highlights the contribution from the internal polymeric lamella.
Taking gravity into account, the major axes of resolution ellipses for neutron diffraction peaks at small scattering vectors all point to a position vertically above the incident beam center on the detector.
A program has been written to display photographic images from 16 96-well plates obtained from high-throughput crystallization trials. Potential hits can be sorted and inspected according the chemical composition of their precipitant.
EDIFF is a software suite for unit-cell determination of three-dimensional nanocrystals from randomly oriented electron diffraction patterns. It also fits and indexes the diffraction patterns.
addenda and errata
Errors in the paper by Ciccariello, Melnichenko & He [J. Appl. Cryst. (2011), 44, 43–51] are corrected.