Evidence is provided that the tridymite component observed in the X-ray diffraction patterns of some sewage sludge ashes (SSAs) should not be interpreted as the tridymite modification of SiO2 but as the tridymite form of AlPO4. This proof is based on a combined X-ray Powder Diffraction (XRD), X-ray fluorescence (XRF) and Mossbauer spectroscopy investigation of two SSAs produced at two fluidized bed incineration facilities, located in different municipalities and operated differently. The structural and chemical characterization was carried out on the ‘as received’ SSA samples as well as on the residues of these two SSAs pretreated by leaching in citric acid. In addition, direct proof is presented that the tridymite form of AlPO4 does crystallize from X-ray amorphous precursors under conditions that mimic the huge heating rate and short retention time (just seconds at T ≈ 850 °C) typical for fluidized bed incinerators.

The ferroic phase transition in LaEr(MoO4)3 has been analyzed for the first time. It has been confirmed that this compound undergoes a phase transition from a tetragonal system (paraelectric-paraelastic phase), with space group P-421 m [β-Gd2(MoO4)3 averaged phase] to an orthorhombic system (ferroelectric-ferroelastic phase), with space group Pba2 [β'-Gd2(MoO4)3 phase] in a reversible process. This phenomenon, together with the observed demixing at high temperature has been studied using different techniques. LaEr(MoO4)3 samples have been obtained by the conventional solid-state synthesis. The thermal dependence of the crystal structure was studied by powder X-ray and neutron diffraction, following a new refining procedure in which the symmetry modes of atomic displacements from the paraelectric-paraelastic structure were analyzed. Dielectric spectroscopy measurements have confirmed the structural results, showing a very smooth phase transition. Finally, calculations within the framework of Density Functional Theory show a behavior of the lattice parameters similar to that observed in our experiments.

X-ray diffraction is commonly used for non-destructive and precise quantitative determination of internal strain distributions. In recent years tomographic imaging has also been established as a powerful tool for precise non-destructive evaluation of internal structure in materials offering submicron resolution 3D imaging of density distributions. “Diffraction Strain tomography” (DST) concept (Korsunsky, Vorster et al. 2006) has been introduced as a means of tomographic reconstruction of two-dimensional internal strain distributions. The application of this approach during in situ loading has been subsequently demonstrated (Korsunsky et al., 2011). In the present study, similar acquisition strategy was used for diffraction data collection from a Ni-base superalloy turbine blade fabricated by DMLS (Direct Metal Laser Sintering, also sometimes referred to as DLD, Direct Laser Deposition). The experiment was conducted on beamline I12 (JEEP) at Diamond Light Source, UK. Each location within the object was multiply “sampled” (i.e. diffraction patterns were collected containing its contribution) by incident X-ray beams travelling through the sample at different angles. The setup of the beamline also allowed to acquire simultaneously a conventional (absorption tomography) reconstruction of the sample shape. The aim of the experiment was to obtain detailed information about the sample shape, structure, and state. The interpretation of diffraction tomography data requires precise calibration of the sample detector distance at different rotations and positions across the sample, and subsequent application of corrections to remove geometry-induced strain aberrations.

Neutron diffraction (ND) was used to investigate the crystallographic preferential orientation (CPO, texture) and structure parameters of four samples of metagabro mylonite collected from the eastern part of the metagabbro sheet at the Stare Mesto belt, Bohemia Massif, Czech Republic. The samples were selected to form a deformation-ordered series with the microstructure varying from non-deformed metagabbro protolith to strongly sheared ultramylonite and amphibole-rich ulramylonite. The specimens used in ND measurements were polished in form of an exact sphere with diameter 50 ± 0.1 mm. The obtained ND patterns were corrected for non-linear background and then evaluated using the Rietveld method implemented in the software package GSAS. Data recorded from powder preparded by milling material from the sampled rocks were used to refine the structure parameters of plagioclase (labradorite structure, triclinic space group C-1) and amphibole (monoclinic space group C2/m). The experiments were performed on the KSN-2 neutron diffractometer situated at the research reactor LVR-15 of the Nuclear Research Institute, plc. Rez, Czech Republic. The data sets of ND patterns measured on each of the four spherical specimens consisted of 90 diagrams collected for different diffraction vectors covering uniformly one orientation hemisphere of the specimen. Based on the collected data, the orientation distribution function (ODF) of crystalline grains was determined by Rietveld harmonic method (coefficients C(l,m,n) of the spherical harmonics expansion determined up to the order L = 8) for the two principal mineral phases - amphibole and plagioclase. The ODF was used to reconstruct (001), (020), (021), (110), (111) (plagioclase) and (001), (11-1), (020), (110), (200) (amphibole) pole figures (PFs). Direct method of ODF calculation implemented in ResMat software package was then used to calculate inverted pole figures (IPFs) of the plagioclase phase. CPO of the amphibole and plagioclase is then discussed in terms of the obtained texture indices and calculated PFs and IPFs and compared with data measured by other methods or available in literature.

Polycrystalline compounds in the Zn1-xNdxCr2Se4 system were prepared by solid state reaction using selenides (ZnSe, Cr2Se3) and pure elements (Nd, Se) as starting materials. The structural properties were determined by X-ray diffraction and the chemical composition confirmed by SEM-EDX. The observed symmetry is cubic, space group Fd3m, while the lattice parameter varies from 10.4955(7)Å to 10.4976(7)Å, and is larger than for the pure matrix. The solubility limit for the current synthesis route lies below x = 0.1. The magnetic moments, effective and saturation, increase with increasing amount of Nd ions. The Neel temperature TN and ΘCW drop, respectively, to 17.4K and 81K for x = 0.1, independently indicating that neodymium is incorporated into the spinel lattice and promotes antiferromagnetic coupling between the Cr3+ ions.

Semifluorinated (SF) side chain polymers show phase separation between polymer backbone and SF side chains. Due to strong interaction between SF segments the side chains determine the structure behaviour strongly, often resulting in layered structures in which backbones and layers of SF side chains alternate. The interest in this work was directed to find out the dependence of these structures on concentration of SF side chains. Thin films of random copolymers consisting of methylmethacrylate (MMA) and semifluorinated side chain methacrylate (SFMA) segments and with different fluorine content in the perfluoroalkyl side chains (abbreviated as H10F10 and H2F8) were prepared by spin-coating. Phase separation and structure changes were initiated by external subsequent annealing. Corresponding bulk material served as basic information. Generation of ordered structures and variation of film parameters were observed using different X-ray scattering methods (XRR, GIWAXS, and GISAXS). The phase behaviour in bulk is governed by the SF side chain amount and their specific fluorine content which control the self-organization tendency of SF side chains. Additionally, the confinement in thin films generates an orientation of side chains normally to film surface.

The Sr analogue of the mineral fresnoite (Sr2TiSi2O8) is of interest as a potential storage medium for radioactive Sr from nuclear waste. No high or low temperature crystal structure information is known on this phase. Therefore high-resolution synchrotron X-ray powder diffraction measurements have been done on a synthetic sample of Sr-fresnoite in the temperature range 87-1223K. This was done as a test experiment using the HRPD beamline P02.1 at PETRA-III, DESY. Synchrotron X-ray wavelengths of 0.2067(3)Å (293K and 573-1223K) and 0.2079(3)Å (87-499K) were used. Powder diffraction data were collected with a counting time of 30s using a PerkinElmer XRD 1621 flat panel image plate detector. CeO2 was included as an internal standard to calibrate the sample to detector distance. The P4bm tetragonal crystal structure of fresnoite (Ba2TiSi2O8) was used as a starting model for Sr-fresnoite. Small amounts of SrTiO3 and SrSiO3 were also found as impurities in this sample; therefore four-phase Rietveld refinements were done. The P4bm fresnoite structure is retained over the temperature range 87-1223K.

PyFAI is an open-source Python library for Fast Azimuthal Integration which provides 1D- and 2D-azimuthal regrouping with a clean programming interface and tools for calibration. The library is suitable for interactive use in Python. In optimising the speed of the algorithms there has been no compromise on the accuracy compared to reference software. Fast integrations are obtained by the combination of an algorithm ensuring that each pixel from the detector provides a direct contribution to the final diffraction pattern and an OpenCL implementation that can use graphics cards for acceleration. This contribution describes how the algorithms were modified to work better in parallel.

Phosphostrontium carbonate hydroxyapatites having the general formula Sr10(PO4)6(OH)(2-2x)(CO3)x were prepared by solid gas reaction at different temperatures in the range 0 ≤ x ≤ 1. Infrared spectroscopy investigation reveals a carbonate groups substituting hydroxyl ions. Intensity bands increasing with the carbonate amount introduced in the lattice, while the one corresponding to hydroxyl decreases until disappearance. The Rietveld refinement of the structural model using X-ray powder diffraction patterns is used to determine the substitution rate. It was quantified by the refinement of the occupancy sites affected by the substitution. The crystallographic study shows the evolution of the atomic coordinate in the apatite due to the carbonate incorporation. The variation of the main interatomic distances and the bond angles was also discussed.

The current report describes the installation and the preliminary commissioning of the Material Science Powder Diffraction (MSPD) beamline at the Spanish synchrotron ALBA-CELLS. The beamline is fully dedicated to powder diffraction techniques and consists of two experimental stations positioned in series: a High Pressure/Microdiffraction station and a High Resolution/High Throughput powder diffraction station.

To gain accuracy and, hence, physical reality of the data acquired by XRD measurements of fibre textures, a technique is elaborated to achieve experimental values, which are free of extinction effects. Its elaboration is based on combining basic definitions of the extinction theory and texture analysis. This technique is applicable to characterization of metal coatings that appear infinitely thick for X-rays. A nickel sample representing <100> + <221> texture components is used as a model. Resultant derived series of data on pole-density distribution of the {200} diffraction pole figure shows that the data corresponding to the main <100> texture component are strongly affected by extinction. On the contrary, due to definitions that require reduction of the intensity distribution to multiples of random density, the extinction-free values of the volume fraction of texture components do not differ substantially from those calculated by standard methods. Evidently, any of the standard methods for volume fraction measurements provides reasonable data if secondary extinction is even disregarded.

Calcium hydroxyl and fluoroapatite (CaHAp and CaFAp) were prepared in the presence of the 2-carboxyletylphosphonic acid (2-CEPA), by hydrothermal method. The incorporation of phosphonic acid within the apatite structure was confirmed by powder XRD, IR and MAS-NMR spectroscopies and SSA. The X-ray powder analysis showed that the cristallinity was not affected by the presence of organic moieties. IR spectroscopy showed new vibration modes related to phosphonate groups. 31P MAS-NMR spectra exhibit new signals, assigned to the presence of organic phosphorus. Specific surface area (SSA) increases with increasing of phosphonate amount, especially for CaHAp. According to these results, a mechanism is proposed for the formation of two types of ionic interaction (-C-O-Ca) and (Ca-O-Porg).

Two polymorphs of Holmium molybdate, known as β'-phase and γ-phase, were prepared by solid state reaction with different thermal treatments. These polycrystalline samples have been studied for the first time by X-ray thermodiffractometry from room temperature up to 1300 K. We found that the initial β'-phase undergoes a transition to a β-phase and then to a γ-phase. The γ (hydrated)-phase, turns to the γ (dehydrated)-phase and then to the β-phase. Each sequence involves a reversible and an irreversible phase transition for Ho2(MoO4)3. Both polymorphs have remarkable physical properties like nonlinear optics, ferroelectricity and negative thermal expansion. We have calculated the linear expansion coefficients of both phases. We have obtained a positive coefficient for the β'-phase and a negative one for the γ-phase. Moreover, we have made a comparison of the obtained coefficients with previous results for other rare earth molybdates.

Monte Carlo domain structure simulation and Debye equation calculation of XRD patterns were used to confirm the formation of domain structure and investigate its peculiarities. Correspondence of simulated XRD patterns with synchrotron powder diffraction experiments is achieved on the conditions that beside of 90o rotations of brownmillerite-like domains inside perovskite-like matrix each domain contains areas with perpendicularly oriented tetrahedral chains. Influence of such parameters as stoichiometry, average domain size, orthorhombic distortion degree on the XRD patterns is considered.

Total Scattering Methods are nowadays widely used for the characterization of defective and nanosized materials. They commonly rely on highly accurate neutron and synchrotron diffraction data collected at dedicated beamlines. Here, we compare the results obtained on conventional laboratory equipment and synchrotron radiation when adopting the Debye Function Analysis method on a simple nanocrystalline material (a synthetic iron oxide with average particle size near to 10 nm). Such comparison, which includes the cubic lattice parameter, the sample stoichiometry and the microstructural (size-distribution) analyses, highlights the limitations, but also some strengthening points, of dealing with conventional powder diffraction data collections on nanocrystalline materials.

Nanocrystalline anatase powders synthesised by various chemical processes as super/subcritical fluid extraction, sol-gel technique and hydrolysis of titanium alkoxides in hydrogen peroxide were studied by X-ray diffraction (XRD) whole profile modelling method (WPPM) in order to reveal correlations between structural and micro-structural parameters as well as sample treatment conditions. Anisotropy of the diffraction line broadening due to truncated bipyramidal shape of anatase crystals was discussed. The hkl-anisotropy can be very strong but also almost negligible in dependence on relative ratio of the crystallite dimensions. The latter was the case for the studied samples. The size of synthesised anatase nanoparticles was within the range 3–25 nm. The theoretical total surface area of crystallites calculated from XRD was in a good correlation with the surface area measured by the nitrogen physisorption up to the temperature 400–450 °C, when the particles started to agglomerate. At atomic scale a unit cell volume contraction with decreasing crystallite size and a significant deficiency in the Ti-site occupancy was observed. Both effects were attributed to the presence of Ti-vacancies and a linear coefficient between the relative cell volume contraction and the fraction of Ti-vacancies was estimated to (–0.017 ± 0.003).

The NaYF4:Yb3+,Tb3+ (x Yb: 0.20, x Tb: 0.04) materials were prepared by the co-precipitation method. The as-prepared material was washed with and without water and thereafter annealed at 500 °C. This resulted in materials with moderate (with water) and very high (without water) up-conversion luminescence intensity. The structural details causing the differences in luminescence intensity were investigated at room temperature with X-ray powder diffraction and Rietveld analyses. All materials crystallized in the hexagonal form (P63/m, No. 176, Z: 1.5) with a composition very close to stoichimetric. The local structural details revealed microstrains in the rare earth sublattice that were relaxed for the material with very high up-conversion luminescence intensity thus decreasing energy losses and enhancing up-conversion.

Linear Friction Welding (LFW) has tremendous potential for joining components from similar and dissimilar materials, avoiding material melting and introducing minimal distortion and only moderate levels of residual stress. However, the significant amount of attendant shear introduces preferred crystal orientations that have not yet been well studied. The “one-shot” approach to the interpretation of multi-element energy-dispersive X-ray powder diffraction data allows preferred orientation analysis without any sample preparation (cutting or polishing) or sample rotation. The key step for texture analysis by X-ray powder diffraction is the derivation of the orientation distribution function (ODF) from experimental data. Matlab toolbox “MTEX” provides a powerful function “calcODF” based on the harmonics method for this purpose. In the study reported in this paper, energy dispersive X-ray diffraction patterns were collected using the “horseshoe” multi-element energy-dispersive Ge detector installed on the JEEP beamline at Diamond Light Source. A single exposure was used for each gauge volume of interest, and a line was scanned across an Aluminum 2024 alloy LFW sample. The patterns were converted into raw pole figures through single peak fitting and equal area projection. The ODF calculation was performed based on these pole figures using Matlab toolbox “MTEX”. As a result, full pole figures obtained after ODF calculation were obtained. These are presented and discussed. The results show that the thermal-mechanical processes that occur during the LFW process lead to significant modification of the orientation distribution, but cause only moderate changes in the texture index.