Having synthesised an AlON-bonded ceramic corundum material, Al5O3N3 (15R) polytype coexisting with α-Al2O3 was identified. The sample was prepared from an alumina-rich mixture of Al2O3 and AlN substrates and fired at 1650 °C in a nitrogen atmosphere. Using the X-ray external standard quantitative method, one of the reaction products, α-Al2O3, was quantified. From the remaining substrates the stoichiometric composition of the second phase was calculated. The applied method of crystal structure determination consisted of three stages. In the first stage, the Le Bail method of X-ray pattern decomposition was used for the extraction of Al5O3N3 (15R) diffraction lines from a two-phase diffractogram. The space group and unit-cell dimensions from the isostructural SiAl4O2N4 SiAlON phase, producing the same X-ray pattern, were used as input data. Next, the direct structure determination in real space was applied for initial structural model derivation, which was followed by Rietveld refinement. The solved crystal structure of Al5O3N3 (15R), except the stacking sequence, proved to be closely related to the structure of Al7O3N5 (21R) polytype. The Al5O3N3 (15R) is trigonal with space group R-3m, unit-cell dimensions a0 = 3.0128 Å, c0 = 41.8544 Å, and volume V = 329.00 Å3. The model of Al5O3N3 (15R) polytype structure has positional disordering in one of three (6c) Al sites, which leads to stacking faults in six tetrahedral layers. Every third tetrahedron from LR3 and LR4, LR8 and LR9, LR13 and LR14 layers is rotated by 180°.

We present a detailed description of the SESAME Materials Science (MS) beamline for X-ray diffraction (XRD) applications, presently under construction in Allan, Jordan. The beamline is based on components previously installed at the Swiss Light Source, but modifications in the beamline design have been introduced to match the characteristics of the SESAME storage ring. The SESAME MS beamline will accommodate XRD experiments in the energy range between 5 and 25 keV. The beamline ray tracing analysis at 10 keV estimates the flux at the sample to be of the order of 1013 (photons s−1), the energy resolution is about 2 eV and the effective beam size at the sample of 300 × 2800 µm2. Investigations of microstruture will be possible as the instrumental broadening, resulted from simulating the diffraction pattern for a standard material, is of the order of 0.01° at 15 keV. A wide range of applications will be possible at the beamline, such as powder diffraction studies, single crystals and in situ XRD. The commisioning of the beamline is expected to be in the second half of 2017.

In this paper, some results of neutron diffraction properties of the double-crystal Si(111) + Si(311) setting containing two bent perfect crystals, but with the second one – analyzer in the fully asymmetric diffraction geometry are presented. Both fully asymmetric diffraction geometries, with the output beam compression as well as the output beam expansion, were tested for the sake of possible applications.

In this work, we developed an X-ray powder diffractometer system equipped with six solid-state detectors and used it to perform ab initio structure determination from the powder diffraction pattern data obtained for a caffeine–oxalic acid co-crystal. The crystal structure obtained from the powder diffraction data was consistent with the previously solved single-crystal structure (Trask reference), although slightly larger (by about 2%). The co-crystallization of pharmaceutically active molecules can modulate their physical properties such as solubility, stability, and bioavailability. For the investigation of pharmaceutical complexes, the ability to visualize molecular interactions such as hydrogen bonding would be very helpful toward understanding their physical properties. Given the rate at which the high-throughput screening of pharmaceutical complexes has grown, an analogous high-volume, high-resolution X-ray powder diffraction technique with high-throughput data collection ability would be useful. We also solved the crystal structures of an inorganic complex and metal organic framework, zinc acetate dihydrate and CPL-1, in order to demonstrate the performance of our new diffractometer system.

In this study, the application of (an)isotropic size determination using a recently proposed model for the double-Voigt approach is demonstrated and validated against line profile simulations using the Whole Powder Pattern Modelling approach. The fitting of simulated line profiles demonstrates that the attained crystallite sizes and morphologies are in very reasonable agreement with the simulated values and thus demonstrate that even in routine application scenarios credible size and morphology information can be obtained using the double-Voigt approximation. The aim of this contribution is to provide a comprehensive introduction to the problem, address the practical application of the developed model, and discuss the accuracy of the double-Voigt approach and derived size parameters. Mathematical formulations for the visualization of modeled morphologies, supporting the application of the recently developed macros, are additionally provided.

Crystal structure determination on the basis of powder diffraction data frequently involves the question how the given diffraction data with some appreciably hkl-dependent line broadening should be interpreted. In many cases, such line broadening may either: (i) reasonably well be reconciled with a certain high-symmetry structure model or (ii) with a variant of the former with lower symmetry crystal family, which frequently will give a somewhat better fit in Rietveld refinement. In this work, it is shown mathematically that symmetry reduction induced reflection spitting masked by other line broadening contributions, thus leading to some reflection splitting-induced line broadening, shows a similar hkl dependence as typically adopted for anisotropic microstrain broadening with respect to the high-symmetry structure. This implies that Rietveld refinement on the basis of the low-symmetry model (including typically isotropic line broadening) and on the basis of the high-symmetry model with anisotropic microstrain broadening can both lead to similar qualities of the fit. Hence, the refinement results for both possibilities should be carefully considered in combination with possibly available additional information (e.g. results of first-principles calculations) to arrive at adequate conclusions concerning the true symmetry of the material under investigation.

Structures of the two M0.50SbFe(PO4)3 (M = Mg, Ni) phases, abbreviated as [Mg0.50] and [Ni0.50], were determined at room temperature from X-ray diffraction (XRD) powder data using the Rietveld analysis. Both compounds belong to the NASICON structural family. XRD patterns of [Mg0.50] and [Ni0.50] phases were easily indexed with a primitive hexagonal unit cell [P$\overline 3 $ space group, Z = 6] similar to that already obtained for La0.33Zr2(PO4)3. Obtained unit cells parameters are [a = 8.3443(1) Å, c = 22.3629(1) Å], and [a = 8.3384(1), c = 22.3456(1) Å], respectively, for [Mg0.50] and [Ni0.50] phosphates. In both samples, the [Sb(Fe)(PO4)3]− NASICON framework is preserved and a partially-ordered distribution of Sb5+ and Fe3+ ions is observed. Raman spectroscopic study was used to obtain further structural information about the nature of bonding in [Mg0.50] and [Ni0.50] phases.

A combination of neutron diffraction, synchrotron X-ray diffraction, and high-resolution extended X-ray absorption fine structure measurements has been used to clarify the correlations between long- and local-range structural distortions across the spin-state transition in powders of LaCoO3 and La0.5Sr0.5Co0.75Nb0.25O3. The analysis of the diffraction data has revealed that the isotropic thermal parameters of Co–O bond abnormally increase below 100 K in both samples, while the temperature dependence of the average Co–O bond lengths is linear from 10 to 300 K. We also have found that the Co–O bond lengths are larger in La0.5Sr0.5Co0.75Nb0.25O3, as compared with the ones in LaCoO3. The X-ray absorption data showed an anomalous decrease of the Co–O bond lengths only for LaCoO3, in contrast to the bond length values obtained by diffraction. The structural anomalies observed by spectroscopy measurements are discussed in terms of the spin-state transition model.

Commercial anodes with different state of charge are investigated by X-ray diffraction technique using Rietveld method for data collected with standard laboratory equipment. It is shown that full profile refinement gives good approximation for quantitative description of the charge/discharge process and may be used for estimation of real state of charge (SoC). Careful analysis of the diffraction profile with Rietveld method allows us to quantitatively distinguish the contribution of different LixC6 phases and estimate the real SoC.

A full-pattern fitting procedure based on the Rietveld method was applied to electron diffraction ring patterns of a two-phase system, exhibiting the co-presence of zinc sulfide (sphalerite) and zinc oxide (Wurtzite). Bright and dark field (DF) images reveal the presence of micrometric aggregates, composed of quasi-spherical nanosized crystallites. These conventional transmission electron microscopy imaging methods provide a general morphological characterization of the specimens although, in the present case, they are not suitable for a detailed characterization of the microstructural features of the analyzed samples. Owing to the overlap and broadening of the diffraction rings of the two phases, DF images cannot provide a satisfactory picture of the individual crystallites of each single phase. To overcome this limit, the mentioned Rietveld approach was applied to model the electron diffraction data. The crystalline domain size and relevant shapes for both phases were successfully evaluated using the proposed methodological approach. The excellent results obtained in the microstructural characterization of the nanostructured multiphase samples demonstrate the capability of this technique, that may represents a fully quantitative method for the routine characterization of crystalline nanomaterials.

The VF3-type compound GaF3 has been studied by high-pressure angle-dispersive X-ray diffraction in the pressure range from 0.0001 to 10 GPa. The compression mechanism was found to be highly anisotropic. The c-axis shows little pressure dependence (≈0.4%), but exhibits negative linear compressibility up to ≈3 GPa where it achieves its maximum length. In contrast, the length of the a-axis is reduced by ≈8.8% at the highest measured pressure and an anomalous reduction in the linear compressibility is observed at 4 GPa. The zero pressure bulk modulus B0 was determined to B0 = 28(1) GPa. The compression mechanism of GaF3 is discussed in terms of deformation of an 8/3/c2 sphere-packing model. The volume reduction of GaF3 is mainly achieved through coupled rotations of the GaF6 octahedra within the entire measured pressure range, which reduces the volume of the cubooctahedral voids. In addition, the volume of the GaF6 octahedra also decreases for p ≲ 4.0 GPa, but remains constant above this pressure. The volume reduction of the GaF6 octahedra is accompanied by an increasing octahedral strain. Isosurfaces of the procrystal electron density are used for visualization of the cubooctahedral voids at different pressures.

The alkaline content of mixed transition metal phosphates Li(1−y)·zNay·zM0.5Fe0.5PO4 (M = Mn, Co; 0 ≤ y < 1; 0.5 ≤ z ≤ 1) was determined by powder X-ray diffraction data by means of Rietveld analysis and multi-fraction models. The compounds LiM0.5Fe0.5PO4 were synthesized via solid-state reactions. Chemical extraction of Li with bromine in acetonitrile yielded well-crystalline Li0.5M0.5Fe0.5PO4. Subsequent reduction with Na2S in acetonitrile gave a product with a triphylite-type phase of the average composition Li0.5Na0.5M0.5Fe0.5PO4 showing a broad distribution of Li-to-Na-ratios. For Rietveld refinements a set of 11 fractions Li1−yNayM0.5Fe0.5PO4 was used to represent the triphylite-type phase and its composition fluctuation. To obtain samples with compositions close to NazM0.5Fe0.5PO4 (z = 0.5 or z = 1) up to two additional cycles of chemical oxidation and reduction were required. Because of a complex distribution of Li and Na within the triphylite-type phase a model of 121 fractions of Li(1−y)·zNay·zM0.5Fe0.5PO4 was developed to enable proper Rietveld refinements. The scaling factors of the 121 fractions were constrained by a bimodal bivariate normality. The evaluation of the pattern revealed a type of passivation, preventing the compound from complete oxidation or reduction of Fe for higher cycle numbers. Hence, no completely Li-free samples could be obtained.

X-ray diffraction data revealed that the initial SiO2/Ag nanocomposite, manufactured in a chemical synthesis process, is mainly composed of silica in amorphous phase (95.5 wt.%), crystalline Ag with a cubic structure (Fm-3m) and cristobalite (SiO2) with a tetragonal structure (P41212) in the amount of 4.2 and 0.3 wt.%, respectively. High-temperature diffraction data revealed high stability of the SiO2/Ag composite up to 1000 °C. High-temperature X-ray diffraction measurements revealed phase cristallization temperatures of silica at 1060 °C for cristobalite and 1080 °C for tridymite as well as temperature of silver evaporation starting from the composite (ca. 1000 °C). Infrared spectroscopy data confirmed the presence of amorphous matrix with embedded silver ions and crystalline compounds in the form of cristobalite and tridymite without silver after thermal treatment.

Nanocrystalline boehmite (gamma-aluminium-oxyhydroxide) is a material of industrial importance, the functionality of which follows from its crystalline microstructure. A procedure for preparing boehmite nanoparticles, comprising the formation of a precipitate by the alkalization of an aqueous solution of aluminium nitrate and subsequent hydrothermal aging, was previously elaborated. The application of an additive (maltitol or tartaric acid) to control the sizes and shapes of crystallites in the produced polycrystalline powder of boehmite was developed. The aim of this work is a study of the effect of the hydrothermal treatment time on nanocrystalline characteristics of boehmite, both in absence and in presence of the additive. The obtained materials were investigated by using X-ray diffraction (XRD) as principal technique and additionally by scanning and transmission electron microscopy. The multi-peak analysis of powder XRD patterns was applied to determine the prevalent crystallite shape, volume-weighted crystallite size distribution, and second-order crystalline lattice strain distribution being principal quantitative characteristics of the crystalline microstructure. Based on these characteristics, three types of the microstructure correlated with the production procedures were observed and discussed in detail. The nanoparticles of boehmites were found to be monocrystalline grains with characteristic habits and sizes of order of ten nanometers weakly dependent on the hydrothermal treatment time.

The structure of the NiTi matrix covered by multi-layer was studied applying X-ray diffraction techniques supported by electron microscopy. Multi-layer was composed from titanium oxide (passivation) followed by mixture of the hydroxyapatite (HAp) and β-tricalcium phosphate (β-TCP) (electrophoresis). Conditions of deposition as well as sintering did not change the nominal ratio of HAp/TCP and saved their original structure. Also, the passivated NiTi matrix and with HAp/TCP-deposited layer did not change structure. However, sintering, done for HAp/TCP consolidation, introduced local differences in the lattice parameter as well as phase composition of the NiTi matrix. In consequence of that, two-steps martensitic transformation occurred in sintered NiTi/TiO2/Hap–TCP composite.

New Ca8−xPbxCdBi(VO4)7 with the whitlockite-type structure were prepared by a standard solid-state method in air. Le Bail decomposition was used to determine unit-cell parameters. Structural refining was carried out by Rietveld's method. It is found that Bi3+ cations located partially in M1 and M2 sites along with calcium, while M3 site is settled in half by Pb2+-ions. Second-harmonic generation demonstrate highest non-linear optical activity and along with dielectric investigations indicate polar space group R3c.

The paper describes an approach for automated crystal structure solution from powder diffraction data using the multi-population genetic algorithm (MPGA). The advantage of using co-evolution with the best individual exchange, compared with the using of the evolution with a single genetic algorithm without interpopulation exchange, is shown. As an example, the paper describes the use of MPGA for solving the [Pt(NH3)5Cl]Br3 crystal structure, having the tetragonal I41/a space group [a = 17.2587(5) Å, c = 15.1164(3) Å, Z = 16, unit-cell volume V = 4502.61(10) Å3]. The MPGA convergence charts and the atomic positions distribution maps of the MPGA populations are given. The description of the final structure solution is also shown.

Two examples of anionic complexes having vapochromic behavior are investigated: [K(H2O)][Pt(ppy)(CN)2] “Pt(ppy)” and [K(H2O)][Pt(bzq)(CN)2] “Pt(bzq)”, where ppy = 2-phenylpyridinate and bzq = 7,8-benzoquinolate. These monohydrate-potassium salts exhibit a change in color from purple to yellow [Pt(ppy)] and from red to yellow [Pt(bzq)] upon heating to 110 °C, and they transform back into the original color upon absorption of water molecules from the environment. Available only in the form of polycrystalline samples, no structural information on such compounds is accessible, due to highly overlapping peaks in powder diffraction profiles. We use in situ Pair Distribution Function measurements on powder samples to investigate the dynamics of the structural changes induced by temperature variations. By means of a multivariate approach, we were able to extract dynamic structural information from collected profiles without using prior knowledge on the static crystal structure of the compounds. The critical temperature and the characteristics of the vapochromic transition have been identified, as well as the main structural changes causing it.

This paper describes new features implemented in the EXPO2014 software and aimed at assisting crystallographers in the use of quantum-chemistry calculations in combination with experimental powder diffraction data. The implemented tools are useful in particular in two important steps of the process of crystal structure determination from powder diffraction data: (1) preparing accurate structural model suitable for crystal structure determination by real-space methods; (2) validating structure determination. The combination of experimental/quantum-chemical methods in EXPO2014 is now managed easily thanks to the following capabilities: (a) converting crystallographic data in input files and reading molecular geometry from output files of a wide variety of computational chemistry packages (GAMESS-US, NWChem, Gaussian, CRYSTAL, ABINIT, QUANTUM ESPRESSO); (b) optimizing the geometry of a molecule using Open Babel's force fields; (c) a graphical interface to run semi-empirical quantum calculation by MOPAC (Molecular Orbital PACkage); (d) producing input file for dispersion-corrected density functional theory.