It is shown that it is possible to perform combined X-ray and neutron single-crystal studies in the same diamond anvil cell (DAC). A modified Merrill–Bassett DAC equipped with an inflatable membrane filled with He gas has been developed. It can be used on laboratory X-ray and synchrotron diffractometers as well as on neutron instruments. The data processing procedures and a joint structural refinement of the high-pressure synchrotron and neutron single-crystal data are presented and discussed for the first time.

Silicon nanowire-based sensors find many applications in micro- and nano-electromechanical systems, thanks to their unique characteristics of flexibility and strength that emerge at the nanoscale. This work is the first study of this class of micro- and nano-fabricated silicon-based structures adopting the scanning X-ray diffraction microscopy technique for mapping the in-plane crystalline strain (∊044) and tilt of a device which includes pillars with suspended nanowires on a substrate. It is shown how the micro- and nanostructures of this new type of nanowire system are influenced by critical steps of the fabrication process, such as electron-beam lithography and deep reactive ion etching. X-ray analysis performed on the 044 reflection shows a very low level of lattice strain (<0.00025 Δd/d) but a significant degree of lattice tilt (up to 0.214°). This work imparts new insights into the crystal structure of micro- and nanomaterial-based sensors, and their relationship with critical steps of the fabrication process.

The microstructures of six stacking-faulted industrially produced cobalt- and aluminium-bearing nickel layered double hydroxide (LDH) samples that are used as precursors for Li(Ni1−x−yCoxAly)O2 battery materials were investigated. Shifts from the brucite-type (AγB)□(AγB)□ stacking pattern to the CdCl2-type (AγB)□(CβA)□(BαC)□ and the CrOOH-type (BγA)□(AβC)□(CαB)□ stacking order, as well as random intercalation of water molecules and carbonate ions, were found to be the main features of the microstructures. A recursive routine for generating and averaging supercells of stacking-faulted layered substances implemented in the TOPAS software was used to calculate diffraction patterns of the LDH phases as a function of the degree of faulting and to refine them against the measured diffraction data. The microstructures of the precursor materials were described by a model containing three parameters: transition probabilities for generating CdCl2-type and CrOOH-type faults and a transition probability for the random intercalation of water/carbonate layers. Automated series of simulations and refinements were performed, in which the transition probabilities were modified incrementally and thus the microstructures optimized by a grid search. All samples were found to exhibit the same fraction of CdCl2-type and CrOOH-type stacking faults, which indicates that they have identical Ni, Co and Al contents. Different degrees of interstratification faulting were determined, which could be correlated to different heights of intercalation-water-related mass-loss steps in the thermal analyses.

The residual strain distribution has been measured as a function of depth in both top coat and bond coat in as-received and heat-treated air plasma sprayed thermal barrier coating samples. High-energy synchrotron X-ray beams were used in transmission to produce full Debye–Scherrer rings whose non-circular aspect ratio gave the in-plane and out-of-plane strains far more efficiently than the sin2ψ method. The residual strain in the bond coat is found to be tensile and the strain in the β phase of the as-received sample was measured. The residual strains observed in the top coat were generally compressive (increasing towards the interface), with two kinds of nonlinear trend. These was a `jump' feature near the interface, and in some cases there was another `jump' feature near the surface. It is shown how these trend differences can be correlated to cracks in the coating.

Grazing-incidence small-angle X-ray scattering (GISAXS) coupled with computed tomography (CT) has enabled the visualization of the spatial distribution of nanostructures in thin films. 2D GISAXS images are obtained by scanning along the direction perpendicular to the X-ray beam at each rotation angle. Because the intensities at the q positions contain nanostructural information, the reconstructed CT images individually represent the spatial distributions of this information (e.g. size, shape, surface, characteristic length). These images are reconstructed from the intensities acquired at angular intervals over 180°, but the total measurement time is prolonged. This increase in the radiation dosage can cause damage to the sample. One way to reduce the overall measurement time is to perform a scanning GISAXS measurement along the direction perpendicular to the X-ray beam with a limited interval angle. Using filtered back-projection (FBP), CT images are reconstructed from sinograms with limited interval angles from 3 to 48° (FBP-CT images). However, these images are blurred and have a low image quality. In this study, to optimize the CT image quality, total variation (TV) regularization is introduced to minimize sinogram image noise and artifacts. It is proposed that the TV method can be applied to downsampling of sinograms in order to improve the CT images in comparison with the FBP-CT images.

Molybdenum oxides and sulfides on various low-cost high-surface-area supports are excellent catalysts for several industrially relevant reactions. The surface layer structure of these materials is, however, difficult to characterize due to small and disordered MoOx domains. Here, it is shown how X-ray total scattering can be applied to gain insights into the structure through differential pair distribution function (d-PDF) analysis, where the scattering signal from the support material is subtracted to obtain structural information on the supported structure. MoOx catalysts supported on alumina nanoparticles and on zeolites are investigated, and it is shown that the structure of the hydrated molybdenum oxide layer is closely related to that of disordered and polydisperse polyoxometalates. By analysing the PDFs with a large number of automatically generated cluster structures, which are constructed in an iterative manner from known polyoxometalate clusters, information is derived on the structural motifs in supported MoOx.

Crystallographic textures, as they develop for example during cold forming, can have a significant influence on the mechanical properties of metals, such as plastic anisotropy. Textures are typically characterized by a non-uniform distribution of crystallographic orientations that can be measured by diffraction experiments like electron backscatter diffraction (EBSD). Such experimental data usually contain a large number of data points, which must be significantly reduced to be used for numerical modeling. However, the challenge in such data reduction is to preserve the important characteristics of the experimental data, while reducing the volume and preserving the computational efficiency of the numerical model. For example, in micromechanical modeling, representative volume elements (RVEs) of the real microstructure are generated and the mechanical properties of these RVEs are studied by the crystal plasticity finite element method. In this work, a new method is developed for extracting a reduced set of orientations from EBSD data containing a large number of orientations. This approach is based on the established integer approximation method and it minimizes its shortcomings. Furthermore, the L1 norm is applied as an error function; this is commonly used in texture analysis for quantitative assessment of the degree of approximation and can be used to control the convergence behavior. The method is tested on four experimental data sets to demonstrate its capabilities. This new method for the purposeful reduction of a set of orientations into equally weighted orientations is not only suitable for numerical simulation but also shows improvement in results in comparison with other available methods.

Small-angle neutron scattering (SANS) was recently applied to the in situ and operando study of the charge/discharge process in Li-ion battery full-cells based on a pouch cell design. Here, this work is continued in a half-cell with a graphite electrode cycled versus a metallic lithium counter electrode, in a study conducted on the SANS-1 instrument of the neutron source FRM II at the Heinz Maier-Leibnitz Zentrum in Garching, Germany. It is confirmed that the SANS integrated intensity signal varies as a function of graphite lithiation, and this variation can be explained by changes in the squared difference in scattering length density between graphite and the electrolyte. The scattering contrast change upon graphite lithiation/delithiation calculated from a multi-phase neutron scattering model is in good agreement with the experimentally measured values. Due to the finite coherence length, the observed SANS contrast, which mostly stems from scattering between the (lithiated) graphite and the electrolyte phase, contains local information on the mesoscopic scale, which allows the development of lithiated phases in the graphite to be followed. The shape of the SANS signal curve can be explained by a core–shell model with step-wise (de)lithiation from the surface. Here, for the first time, X-ray diffraction, SANS and theory are combined to give a full picture of graphite lithiation in a half-cell. The goal of this contribution is to confirm the correlation between the integrated SANS data obtained during operando measurements of an Li-ion half-cell and the electrochemical processes of lithiation/delithiation in micro-scaled graphite particles. For a deeper understanding of this correlation, modelling and experimental data for SANS and results from X-ray diffraction were taken into account.

An error in the article by Gao, Zhang, Zhu, Wu, Mo, Pan, Liu & Jiang [J. Appl. Cryst. (2019), 52, 637–642] is corrected.

A historical tool for crystallographic analysis is provided by the Hilton net, which can be used for manually surveying the crystal lattice as it is manifested by the Kikuchi bands in a gnomonic projection. For a quantitative analysis using the Hilton net, the projection centre as the relative position of the signal source with respect to the detector plane needs to be known. Interplanar angles are accessible with a precision and accuracy which is estimated to be ≤0.3°. Angles between any directions, e.g. zone axes, are directly readable. Finally, for the rare case of an unknown projection-centre position, its determination is demonstrated by adapting an old approach developed for photogrammetric applications. It requires the indexing of four zone axes [uvw]i in a backscattered Kikuchi diffraction pattern of a known phase collected under comparable geometric conditions.

A method of simulating the neutron scattering by a textured polycrystal is presented. It is based on an expansion of the scattering cross sections in terms of the spherical harmonics of the incident and scattering directions, which is derived from the generalized Fourier expansion of the polycrystal orientation distribution function. The method has been implemented in a Monte Carlo code as a component of the McStas software package, and it has been validated by computing some pole figures of a Zircaloy-4 plate and a Zr–2.5Nb pressure tube, and by simulating an ideal transmission experiment. The code can be used to estimate the background generated by components of neutron instruments such as pressure cells, whose walls are made of alloys with significant crystallographic texture. As a first application, the effect of texture on the signal-to-noise ratio was studied in a simple model of a diffraction experiment, in which a sample is placed inside a pressure cell made of a zirconium alloy. With this setting, the results of two simulations were compared: one in which the pressure-cell wall has a uniform distribution of grain orientations, and another in which the pressure cell has the texture of a Zr–2.5Nb pressure tube. The results showed that the effect of the texture of the pressure cell on the noise of a diffractogram is very important. Thus, the signal-to-noise ratio can be controlled by appropriate choice of the texture of the pressure-cell walls.

This paper reports an Fe-added Y2O3 crucible which is capable of balancing the solution spontaneously and is employed to effectively enhance the homogeneity of YBa2(Cu1−xFex)3O7−δ single crystals.

BEATRIX, is a new tool for performing data analysis of energy-resolved neutron-imaging experiments involving intense fitting procedures of multi-channel spectra. The use of BEATRIX is illustrated for a test specimen, providing spatially resolved 2D maps for residual strains and Bragg edge heights.

A new temperature-controllable humidifier for X-ray diffraction has been developed. It is shown that the humidifier can successfully maintain protein crystal growth at a temperature lower than room temperature.

An X-ray cross-correlation study of the impact of ligand composition and salt content on the self-assembly of soft-shell nanoparticles is presented, indicating symmetry-selective formation of order.

Because researchers do not understand the formation mechanism of cocrystals, the preparation of cocrystals is mostly done by trial and error. This study focuses on the cocrystal formation mechanism to improve the efficiency of cocrystal preparation.

By using small-angle neutron scattering (SANS) reinforced by scanning electron microscopy, the fine structure of catalysts for polymer electrolyte fuel cells has been investigated. The experimental data resulting from contrast variation with mixed light and heavy water (H2O/D2O) are well described by a core–shell model with fluctuations in concentration between water and Nafion.

This work describes a method to characterize the size distribution of individual aqueous droplets in a high-density and polydisperse aerosol. It is shown that droplets smaller than 120 nm can be generated by purely mechanical means using a gas dynamic virtual nozzle, and theoretical models are provided for the different flow regimes investigated.

Book review

The effects of relative humidity on a tetragonal crystal form of hen egg white lysozyme are studied via in situ laboratory X-ray powder diffraction.

Book review

The design and assembly of two 3D-printed holders for high-throughput in meso in situ fixed-target crystallographic data collection are described.

A calculation procedure for X-ray total scattering and the pair distribution function from a crystalline structural model is presented. It allows one to easily and precisely deal with diffraction-angle-dependent parameters such as the atomic form factor and the resolution of the optics.

This study demonstrates a new preparation method for single-crystal X-ray diffraction samples using a focused ion beam. The results of the structure determination and electron density maps with differently prepared samples are discussed, to evaluate this new method.

This article describes rational strategies for the optimization of crystal growth using precise in situ control of the temperature and chemical composition of the crystallization solution through dialysis, to generate crystals of the specific sizes required for different downstream structure determination approaches.

A new approach to variable-temperature measurements is presented, where the sample temperature changes continuously as a function of position.

This article presents the capability of the QMAX furnace, devoted to reciprocal space mapping through X-ray scattering at high temperature up to 2000 K.

Instrumentation for sub-millisecond time-resolved small-angle neutron scattering measurements at NIST is described and applied to the reorientation dynamics of elongated hematite nanoparticles.

Exact and approximate formulas for equatorial aberration of a continuous-scan Si strip detector are compared.

Neutron crystal structure analysis of hen egg-white lysozyme hydrogen/deuterium exchanged before crystallization were performed by the joint X-ray and neutron refinement. The differences in hydrogen/deuterium exchange behavior between this study and previous ones were observed.

EDDIDAT is a program that provides a graphical user interface (GUI) for the evaluation of energy-dispersive X-ray diffraction data with the focus on the depth-resolved residual stress analysis.

The crystal structure of the organic pigment 2-monomethyl-quinacridone (Pigment Red 192, C21H14N2O2) was solved from X-ray powder diffraction data. The resulting average structure is described in space group Poverline 1, Z = 1 with the molecule on the inversion centre. The molecules are arranged in chains. The molecules, which have no inversion symmetry, show orientational head-to-tail disorder. In the average structure, the methyl group is disordered and found on both ends of the molecule with an occupancy of 0.5 each. The disorder and the local structure were investigated using various ordered structural models. All models were analysed by three approaches: Rietveld refinement, structure refinement to the pair distribution function (PDF) and lattice-energy minimization. All refinements converged well. The Rietveld refinement provided the average structure and gave no indication of a long-range ordering. The refinement to the PDF turned out to be very sensitive to small structural details, giving insight into the local structure. The lattice-energy minimizations revealed a significantly preferred local ordering of neighbouring molecules along the [0ar 11] direction. In conclusion, all methods indicate a statistical orientational disorder with a preferred parallel orientation of molecules in one direction. Additionally, electron diffraction revealed twinning and faint diffuse scattering.

In this work, the mechanism of solvent-mediated desolvation transformation of lenvatinib mesylate (LM) was investigated. Two new solid forms of LM, a dimethyl sulfoxide (DMSO) solvate and an unsolvated form defined as form D, were discovered and characterized using powder X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, polarized light microscopy and Raman spectroscopy. To investigate the thermodynamic mechanism of solvent-mediated desolvation transformation (SMDT) from LM DMSO solvate to form D, solubilities of LM DMSO solvate and form D in binary solvent mixtures of DMSO and water at different water volume fractions and temperatures (293.15–323.15 K) were measured and correlated by non-random two liquids model. The solubility data were used to evaluate the thermodynamic driving force of the SMDT process from DMSO solvate to form D and the effect of the activities of water and DMSO on the transformation process. Raman spectroscopy was used to monitor in situ the solid phase compositions during the SMDT process from LM DMSO solvate to form D while the solution concentration was measured by the gravimetric method. The overall desolvation transformation experiments demonstrated that the SMDT process was controlled by the nucleation and growth of form D. Moreover, effects of operating factors on the SMDT process were studied and the results illustrated that water activity in solution was the paramount parameter in the SMDT process. Finally, a new SMDT mechanism was suggested and discussed.

The proton-conducting material (NH4)4H2(SeO4)3 is examined to check whether its conductivity spectra are sensitive to subtle changes in the crystal structure and proton dynamics caused by external pressure. The AC conductivity was measured using impedance spectroscopy, in the frequency range from 100 Hz to 1 MHz, at temperatures 260 K < T < 400 K and pressures 0.1 MPa < p < 500 MPa. On the basis of the impedance spectra, carefully analyzed at different thermodynamic conditions, the p–T phase diagram of the crystal is constructed. It is found to be linear in the pressure range of the experiment, with the pressure coefficient value dTs/dp = −0.023 K MPa−1. The hydrostatic pressure effect on proton conductivity is also presented and discussed. Measurements of the electrical conductivity versus time were performed at a selected temperature T = 352.3 K and at pressures 0.1 MPa < p < 360 MPa. At fixed thermodynamic conditions (p = 302 MPa, T = 352.3 K), the sluggish solid–solid transformation from low conducting to superionic phase was induced. It is established that the kinetics of this transformation can be described by the Avrami model with an effective Avrami index value of about 4, which corresponds to the classical value associated with the homogeneous nucleation and three-dimensional growth of a new phase.

This work presents the crystal structure determination of two elusive polymorphs of furazidin, an antibacterial agent, employing a combination of crystal structure prediction (CSP) calculations and an NMR crystallography approach. Two previously uncharacterized neat crystal forms, one of which has two symmetry-independent molecules (form I), whereas the other one is a Z' = 1 polymorph (form II), crystallize in P21/c and P1 space groups, respectively, and both are built by different conformers, displaying different intermolecular interactions. It is demonstrated that the usage of either CSP or NMR crystallography alone is insufficient to successfully elucidate the above-mentioned crystal structures, especially in the case of the Z' = 2 polymorph. In addition, cases of serendipitous agreement in terms of 1H or 13C NMR data obtained for the CSP-generated crystal structures different from the ones observed in the laboratory (false-positive matches) are analyzed and described. While for the majority of analyzed crystal structures the obtained agreement with the NMR experiment is indicative of some structural features in common with the experimental structure, the mentioned serendipity observed in exceptional cases points to the necessity of caution when using an NMR crystallography approach in crystal structure determination.

The crystal structure of the mineral malayaite has been studied by single-crystal X-ray diffraction at a temperature of 20 K and by calculation of its phonon dispersion using density functional perturbation theory. The X-ray diffraction data show first-order satellite diffraction maxima at positions q = 0.2606 (8)b*, that are absent at room temperature. The computed phonon dispersion indicates unstable modes associated with dynamic displacements of the Ca atoms. The largest-frequency modulus of these phonon instabilities is located close to a wavevector of q = 0.3b*. These results indicate that the malayaite crystal structure is incommensurately modulated by static displacement of the Ca atoms at low temperatures, caused by the softening of an optic phonon with Bg symmetry.

A detailed study on chiral compound structures found in the Cambridge Structural Database (CSD) is presented. Solvates, salts and co-crystals have intentionally been excluded, in order to focus on the most basic structures of single enantiomers, scalemates and racemates. Similarity between the latter and structures of achiral monomolecular compounds has been established and utilized to arrive at important conclusions about crystallization of chiral compounds. For example, the fundamental phenomenon of conglomerate formation and, in particular, their frequency of occurrence is addressed. In addition, rarely occurring kryptoracemates and scalemic compounds (anomalous racemates) are discussed. Finally, an extended search of enantiomer solid solutions in the CSD is performed to show that there are up to 1800 instances most probably hiding among the deposited crystal structures, while only a couple of dozen have been previously known and studied.

A study on chiral monomolecular compound structures found in the Cambridge Structural Database is presented.

The proton-conducting crystal (NH4)4H2(SeO4)3 is examined to check whether its conductivity spectra and the phase transition to the superprotonic phase are sensitive to subtle changes in the crystal structure and proton dynamics caused by various thermodynamic conditions. It is established that the kinetics of this transformation can be described using the Avrami model with an effective Avrami index value associated with homogeneous nucleation and three-dimensional growth of a new phase.

The crystal structure of malayaite, CaSnOSiO4, at T = 20 K has been refined, based on the presence of satellite reflections with a modulation vector of 0.26b*. The structural modulation is attributed to a soft optic phonon, dominated by motion of the Ca atoms.

The solvent-mediated desolvation process of newly discovered lenvatinib DMSO solvate to form II at different water volume fractions and temperatures was investigated. It is confirmed that the activity of water is the most important factor affecting the desolvation process: the desolvation process only occurs when the activity of water is greater than the activity of DMSO, and one new mechanism of solvent-mediated desolvation process was proposed.

The crystal structure of the nanocrystalline pigment mono­methyl-quinacridone was solved from X-ray powder data. The orientational disorder was investigated using Rietveld refinements, structure refinement to the pair-distribution function, and lattice-energy minimizations of various ordered structural models.

The synthesis, characterization and study of structures from a series of bi­phenyls substituted at positions 3, 3', 4 and 4' with groups connected to the bi­phenyl core through oxygen atoms are presented here. The molecular conformation is extensively studied both in the solid as well as in the liquid state, and the effect of different actors (such as packing and chain length) on the torsion angle between aromatic rings is analyzed.

A new ZnII metallocryptand is presented, with an unprecedented diflexure helix.

The crystal structure of Pseudomonas aeruginosa Fis is composed of an N-terminal flexible loop and a C-terminal helix–turn–helix motif.

This article reports conformational polymorphisms of the EF-hand protein MCFD2 which is involved in glycoprotein transport..

Aerobic thermoacidophilic archaea belonging to the genus Sulfolobus harbor peroxiredoxins, thiol-dependent peroxidases that assist in protecting the cells from oxidative damage. Here, the crystal structure of the 1-Cys peroxiredoxin from Sulfolobus islandicus, named 1-Cys SiPrx, is presented. A 2.75 Å resolution data set was collected from a crystal belonging to space group P212121, with unit-cell parameters a = 86.8, b = 159.1, c = 189.3 Å, α = β = γ = 90°. The structure was solved by molecular replacement using the homologous Aeropyrum pernix peroxiredoxin (ApPrx) structure as a search model. In the crystal structure, 1-Cys SiPrx assembles into a ring-shaped decamer composed of five homodimers. This quaternary structure corresponds to the oligomeric state of the protein in solution, as observed by size-exclusion chromatography. 1-Cys SiPrx harbors only a single cysteine, which is the peroxidatic cysteine, and lacks both of the cysteines that are highly conserved in the C-terminal arm domain in other archaeal Prx6-subfamily proteins such as ApPrx and that are involved in the association of dimers into higher-molecular-weight decamers and dodecamers. It is thus concluded that the Sulfolobus Prx6-subfamily protein undergoes decamerization independently of arm-domain cysteines.

Described here are instructions for building and using an inexpensive automated microscope (AMi) that has been specifically designed for viewing and imaging the contents of multi-well plates. The X, Y, Z translation stage is controlled through dedicated software (AMiGUI) that is being made freely available. Movements are controlled by an Arduino-based board running grbl, and the graphical user interface and image acquisition are controlled via a Raspberry Pi microcomputer running Python. Images can be written to the Raspberry Pi or to a remote disk. Plates with multiple sample wells at each row/column position are supported, and a script file for automated z-stack depth-of-field enhancement is written along with the images. The graphical user interface and real-time imaging also make it easy to manually inspect and capture images of individual samples.

Archaea are motile by the rotation of the archaellum. The archaellum switches between clockwise and counterclockwise rotation, and movement along a chemical gradient is possible by modulation of the switching frequency. This modulation involves the response regulator CheY and the archaellum adaptor protein CheF. In this study, two new crystal forms and protein structures of CheY are reported. In both crystal forms, CheY is arranged in a domain-swapped conformation. CheF, the protein bridging the chemotaxis signal transduction system and the motility apparatus, was recombinantly expressed, purified and subjected to X-ray data collection.