K3Al3F12⋅nH2O (n=2,1) are the successive products of the thermal decomposition of K(H3O)2AlF6. Both structures are orthorhombic, built up from disconnected hexagonal-tungsten-bronze (HTB)-related layers, with K+ cations and H2O molecules inserted between. For n=2, there are two disconnected layers along a presenting different octahedra tilting [a=13.5135(2) Å, b=7.0433(1) Å, c=12.2252(2) Å, V=1163.60(3) Å3, Z=4, space group Pnma], whereas for n=1, the stacking is reduced to only one HTB layer along c [a=7.0523(5) Å, b=12.1005(9) Å, c=6.7057(5) Å, V=572.24(7) Å3 (at 170 °C), Z=2, space group Pmmn] after the departure of one water molecule. The thermodiffractometry ends in the α-KAlF4 form.

Crystal structure and structural disorder of Ba3MgSi2O8 were reinvestigated by laboratory X-ray powder diffraction. The title compound was found to be trigonal with space group P3m1, Z=1, and unit-cell dimensions a=0.561 453(4) nm, c=0.727 629(4) nm, and V=0.198 641(2) nm3. The initial structural model used for structure refinement was taken from that of glaserite (K3NaS2O8) and modified by a split-atom model. In the split-atom model, one of the two types of Ba sites and that of SiO4 tetrahedra were, respectively, positionally and orientationally disordered. The new crystal structure and structural disorder were refined by the Rietveld method. The maximum-entropy-method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The final reliability indices calculated from MPF were Rwp=6.52%, S=1.36, Rp=4.84%, RB=0.97%, and RF=0.52%. Details of the disorder structure of Ba3MgSi2O8 are shown in the three-dimensional and two-dimensional electron-density distribution maps determined by MPF.

θ-KAlF4 is a new nanosized potassium tetrafluoroaluminate metastable polymorph (13×18×55 nm3). The crystal structure is solved ab initio from X-ray powder diffraction data in direct space [orthorhombic unit cell with a=8.3242(3) Å, b=7.2502(3) Å, c=11.8875(4) Å, V=717.44(5) Å3, Z=8, and space group Pnma]. This new structure type, unique in the whole AIMIIIF4 family, is related to the fluorite structure and consists of AlF6 octahedra linked via a common edge forming a bioctahedral motif which is trans-connected through the corner-shared fluorine, resulting in the formation of infinite ladderlike double file of octahedra ([Al2F8]2−)n running along the b axis.

ZnSe-based heterostructures grown on GaAs substrates have been investigated for use in pin-diode LED applications. In this study, a conventional Bragg-Brentano diffractometer (BBD) has been used to screen samples for phase identification, crystallite size, presence of polycrystalline ZnSe, and initial rocking curve (RC) analysis. A limitation of the conventional diffractometer is that the smallest RC full width at half maximum (FWHM) that can be achieved is 500 to 600 arc sec. As deposition parameters are optimized and the RC limit of the conventional diffractometer is reached, analysis is moved to a four-bounce high-resolution diffractometer (HRD). Although more time for analysis is required, using the HRD has a RC resolution advantage, where RCs of <20 arc sec are obtained for neat GaAs wafers. Combining the BBD and HRD instruments for analysis of ZnSe films grown on GaAs substrates allows for an efficient means of high sample throughput combined with an accurate measurement of film alignment.

The crystal structure of K2Zn(PO3)4 was determined and refined using the Rietveld method based on the isostructure model of K2Cu(PO3)4. This compound belongs to the monoclinic system with space group Cc and lattice parameters of a=11.0941(2) Å, b=12.5215(3) Å, c=7.6597(2) Å, and β=102.47(2)°. The chemical formula unit per unit cell is Z=4 and the calculated density is 2.938(3) g∕cm3. Zigzag [PO3]∞ chains formed along the a axis, and their period contains eight PO4 tetrahedrons.

Residual stress states in engineering structures are usually determined by measuring components of stress tensors with depth below the material surface. There are destructive and nondestructive methods to measure strain tensor components and convert them into stress tensor components by a variety of techniques derived from constitutive (material) equations. In this study, four methods for determining the strain tensor components are presented: X-ray diffraction method (XRDM), magnetic Barkhausen noise method (MBNM), hole drilling method (HDM), and cut-and-section method (CSM); the first two are nondestructive, and the third and fourth are semidestructive and destructive, respectively. A complementarity of the experimental and two numerical methods such as boundary element method and finite element method is explained. An application of the experimental and numerical methods to measure residual stress states in an industrial component, an L-shaped part of a supporting column in a high voltage structure, is presented.

A model for the long awaited crystal structure of metastable NaAlF4 is established from the powder diffraction pattern of a partly disproportionated sample. Orthorhombic, Cmcm, a=3.6121(3), b=14.952(1), c=5.2692(4) Å, Z=4, V=284.58(4) Å3. Sodium atoms are in NaF6 trigonal prisms interconnected by edges in compact layers. AlF6 octahedra are both cis- and trans-corner connected forming a layer structure similar to that observed in the NaNbO2F2 (P21/c) and BaZnF4 (Cmc21) structure types. NaAlF4 is ideally simple and symmetrical, isostructural with BiReO4 (Cmcm), representing the aristotype of the NaMIIIF4 and BaMIIF4 series.

Powder diffraction experiments performed as a function of external variables like, e.g., temperature, pressure, or time open possibilities to gain additional information about the physical and chemical properties of the system under study. Sensible extraction of such information directly from in situ experiments requires the treatment of the dataset with methods like sequential and/or parametric refinements. We are progressing towards the development of the parametric refinement method, which performs simultaneous phase refinements of in situ powder patterns by imposing several rational physical models of the evolving parameters on the calculated powder diffraction profiles. One of the fundamental prerequisites for this method is that the powder patterns in the in situ dataset be grouped to their relevant phases. In this paper, we present an analytical method which uses the Pearson’s correlations coefficients of the powder patterns to automatically determine the phase transition points of the in situ powder dataset. The phase transition points determined are used to group the powder patterns belonging to identical phases and to prepare the patterns for automated sequential phase refinements. The proposed algorithm is implemented as an automated module in the multi powder diffraction pattern, data reduction software Powder 3D.

Using X-ray grazing incidence diffraction (GID) it is possible to perform a nondestructive analysis of the heterogeneous stress field for different volumes below the surface of the sample. The stress can be measured at very small depths, of the order of a few μm. The penetration depth of radiation is almost constant in a wide 2θ range for a given incidence angle α. It can be easily changed by an appropriate selection of α angle (or also by using a different type of radiation). There are, however, some factors which have to be corrected in this technique. The most important is the refraction of X-ray wave: it changes the wavelength and direction of the beam. Both effects modify a pick position. A corresponding correction was calculated and tested on ferrite powder and on 316L austenite stainless steel sample.

A new ternary phase, Er2Cu10.9Ga6.1, has been found in the Er-Cu-Ga phase diagram. X-ray powder diffraction data were successfully refined based on a rhombohedral Th2Zn17 structure type (space group R-3m, No. 166) with cell parameters a=8.6627(1) Å, c=12.6824(2) Å, and Z=3. Er2Cu10.9Ga6.1 exhibits a paramagnetic Curie-Weiss behaviour down to 2 K with a trivalent character of Er atoms.

Activation energies for the intermixing reaction of textured metal-metal multilayer thin films have been determined using X-ray diffraction analysis. Kinetic data were collected utilizing an area detector so as to reduce intensity bias from changes in out-of-plane texture during the intermixing reaction. Activation energies for Al/Pt, Ni/Ti, and Co/Al metal-metal multilayer thin films have been determined as 95.4(2) kJ/mol, 201(13) kJ/mol, and 247(19) kJ/mol, respectively.

The solid-state phase transformation from α- to β-copper phthalocyanine, using isothermal data obtained at T=250 °C and nonisothermal data obtained in the temperature range of 30 °C≤T≤330 °C with a constant heating rate of 1.67 °/min, was investigated by sequential and parametric full quantitative Rietveld analyses. Results obtained in this study show that the parametric Rietveld refinement technique is most suitable and applicable for kinetic studies of isothermal powder diffraction data. On the other hand, the sequential Rietveld refinement technique can give reliable results for the kinetic analysis of nonisothermal data. The main advantages of the parametric Rietveld refinement over the sequential Rietveld refinement are increased robustness against outliers, low weight fractions, and noisy data and an increase in computational speed.