Coatings of plasma sprayed hydroxyapatite (HAp), incubated in simulated body fluid for periods varying from 1 to 56 days, were characterized using conventional laboratory X rays. Quantitative phase analysis, employing TOPAS software, showed an opposite trend in the two main phases of the coating, viz., HAp and tetracalcium phosphate (TTCP). The former increased within the first 7 days of incubation whilst the latter decreased during the same period; both phases stabilized with further incubation. The crystallinity of the coatings exhibited a trend similar to that of HAp i.e., an increase in the early stages of incubation stabilization with further incubation. Results of residual stress determined with Bruker’s D8 Discover and analyzed with LEPTOS software, showed both the normal stress tensor components, σ11 and σ22, to be tensile, relaxing significantly in the early stages of incubation before stabilizing with further incubation.

The family of zeolitic imidazolate framework (ZIF) compounds is efficient sorbent materials that can be used for catalytic, ion exchange, gas storage, and gas separation applications. A high-resolution reference X-ray powder diffraction pattern for one of the ZIF members, bis(2-methylimidazolyl)-zinc, C8H10N4Zn (commonly known as ZIF-8), was determined using synchrotron diffraction data obtained at the Advanced Photon Source (APS) in Argonne, IL. The sample was confirmed to be cubic I-43m, with a = 17.01162(6) Å, V = 4932.08 Å3, and Z = 12. The reference X-ray powder diffraction pattern has been submitted for inclusion in the Powder Diffraction File (PDF).

A detailed neutron powder diffraction study of the atomic structure of α-Bi2O3 at high temperatures using the Rietveld method was performed to clarify the nature of the unusual magnetic behavior and the origin of the high temperature dielectric anomalies of α-Bi2O3 in the temperature interval 300–700 K. Analysis of obtained experimental data shows that there are no evidence of a structural phase transition in α-Bi2O3 between 295 and 660 K. The observed high temperature dielectric anomalies in α-Bi2O3 are evidently governed by changes in the electron subsystem of the bismuth oxide.

Ge–Si inverted huts, which formed at the Si∕Ge interface of Si∕Ge superlattice grown at low temperatures, have been measured by X-ray diffraction, grazing incidence X-ray specular and off-specular reflectivities, and transmission electron microscopy (TEM). The surface of the Si∕Ge superlattice is smooth, and there are no Ge–Si huts appearing on the surface. The roughness of the surfaces is less than 3 Å. Large lattice strain induced by lattice mismatch between Si and Ge is found to be relaxed because of the intermixing of Ge and Si at the Si∕Ge interface.

A simple ashing procedure for a mixture containing kaolinite and chrysotile is described that converts kaolinite to amorphous metakaolinite while retaining the diffraction intensity of chrysotile. This ashing procedure removes the X-ray diffraction (XRD) pattern overlap between kaolinite and chrysotile that can interfere with the analysis of even high concentrations of chrysotile. Samples are ashed at 460 °C in a muffle furnace for 40 h to completely convert kaolinite to metakaolinite. The complete conversion of 1 g of kaolinite under these conditions was determined for two standard kaolinite samples from Georgia, KGa-1 and KGa-2. Two of the most common types of commercial chrysotile, long-fiber Canadian and short-fiber Californian chrysotile, are demonstrated to retain diffraction intensity after ashing at 460 °C. Both chrysotile samples have the same integrated intensity for the (002) reflection prior to ashing, although the peak breadths for the two samples are quite different. Ashing at 480 and 500 °C reduces the diffraction intensities of both chrysotile samples by 15%, and broadens the peaks by approximately 3%. Using the prescribed ashing procedure and x-ray diffraction with an internal corundum standard, two kaolinite-bearing building materials containing chrysotile near 0.01 mass fraction were analyzed. The ashing procedure has additional advantages in reducing some samples to powders and removing volatile components, thereby eliminating some sample preparation procedures and concentrating any chrysotile present in the sample. The removal of volatile components improves the sensitivity of XRD analysis to concentrations below 0.01 mass fraction chrysotile.

High-resolution powder X-ray diffraction has been used to determine the crystal structure of silver behenate, [Ag(O2C(CH2)20CH3]2. Using CASTEP density functional plane wave pseudopotential techniques to obtain an optimized structural model, Rietveld refinement of the structure gives Rwp = 8.66%. The unit cell is triclinic, space group P1, with cell dimensions of a = 4.1769(2) Å, b = 4.7218(2) Å, c = 58.3385(1) Å, α = 89.440(3)°, β = 89.634(3)°, γ = 75.854(1)°. The structure is characterized by an 8-membered ring dimer of Ag atoms and carboxyl groups with a fully extended all-trans configuration of the alkyl side chains. The dimers are joined by four-membered Ag-O rings creating a polymeric network, giving rise to one-dimensional chains along the b-axis. This structure is supported by EXAFS measurements of the local structure around the silver atoms and IR measurements.

In order to better characterize metal soaps found in paint films or on metal surfaces, several metal soaps were synthesized and their X-ray powder diffraction patterns measured. Metal soaps were obtained from four different fatty acids found in drying oils, two saturated (palmitic and stearic acids) and two unsaturated (oleic and linoleic acids), and from copper, zinc, and lead, three metals that are typically found in metal alloys and paint systems. X-ray powder diffraction data are reported for the following compounds: palmitic acid, stearic acid, zinc palmitate, zinc stearate, zinc oleate, zinc linoleate, copper palmitate, copper stearate, copper oleate, lead palmitate, lead stearate, and lead oleate. Features that are characteristic of specific compounds were observed. Soaps obtained from different fatty acids with the same metal ion show differences, as do soaps obtained with the same fatty acid but with different metal ions. Differences were observed when X-ray powder diffraction data obtained for stearic acid and zinc stearate were compared to published data for these two compounds (PDF 38-1923 and 5-0079, respectively). In the case of stearic acid, differences could be explained by the fact that the specimen reported previously in PDF 38-1923 was likely contaminated with palmitic acid. In the case of zinc stearate, low angle data were missing from the original pattern PDF 5-0079 and peaks that were reported in other angular regions in fact consisted in more peaks that were not resolved due to broadening.

Two XRD specimen holders we designed for use with highly radioactive specimens are described. An injection mold was fabricated to allow inexpensive production of one of the holders. These holders are suitable for single-time use. The ease of use and disposable nature of this holder resulted in a dramatic reduction in personnel exposure and an uncontaminated diffraction unit. A second holder, based on the design of the first, is used to obtain XRD patterns from powders where preferred orientation is an issue and from clays. Both holders result in negligible background, since the specimen is essentially levitated in the X-ray beam. This is a benefit over other methods, such as collodion, that introduce significant background to the XRD pattern.

The fluorite-related anion-excess β-Pb1−xFexF2+x (0.25 ≤ x ≤ 0.27) orthorhombic crystal structure is approached from powder diffraction data. A 1 × 1 × 2 fluorite supercell is found to describe the main aspects of the structure, which would have ideally the Pb3FeF9 formula (x = 0.25) (space group Cmmm, a = 5.9926(1), b = 5.5781(1), c = 11.5208(3) Å), and would include a complete [FeF4]∝−1 perovskite plane, orthogonal to the c axis. However, there is large Pb substitution (44%) on the perovskite Fe site as well as Fe substitution (∼25%) on one of the two main Pb sites. A strong relationship with the fully ordered crystal structure of Pb8MnFe2F24, which can be expressed as Pb1−xMxF2+2/3x (x = 0.273), is discussed, suggesting that both phases may have infinite [M3F14]∝ ribbons in common.

The structure of 3,4-diaminopyridin-1-ium dihydrogen phosphate, [C5H3(NH)(NH2)2]+ (H2PO4)−, is solved from conventional X-ray powder diffraction data in direct space (monoclinic unit cell with a = 16.0725(9) Å, b = 7.7301(3) Å, c = 14.6189(9) Å, β = 96.869(1)°, V = 1803.2(2) Å3, Z = 8, and space group I2/c), and optimized by energy minimization in the solid state. In the crystal structure of the title compound, dihydrogenphosphate tetrahedra are linked by strong hydrogen O-H…O bonds forming chains running parallel to the b-axis. Antiparallelly π–π stacked DAP cations form molecular columns in the spaces between the chains. Although the dominant interaction of the molecules with their surroundings is electrostatic, their bonding are further enhanced by N-H…O and C-H…O hydrogen bonds.

The capacity of goethite for CdII substitution has been explored in a series of synthetic samples prepared from FeIII and CdII nitrate solutions aged 21 days in alkaline media. The total metal content ([Fe]+[Cd]) was 0.071 M in all preparations. The samples have been characterized by chemical and X-ray diffraction analysis; the morphology of the solids is described. The cell parameters for all samples were obtained by the Rietveld fits to the X-ray diffraction data. Refined structures show that for samples prepared at the final molar ratio μCd≤5.50 (expressed as μCd=100×[Cd]/[Cd]+[Fe]), a (Cd, Fe)-goethite is the only crystalline product. In these samples, the unit cell parameters increased as a function of Cd concentration, indicating Cd incorporation in the structural frame. At the preparative ratio, μCd=7.03, the incorporation of Cd in the goethite structure is drastically reduced and a probable Cd-substituted hematite is formed together with the Fe,Cd-goethite.

An in situ time-resolved XRD system for hydrothermal reaction has been developed in order to investigate the phase evolution during autoclave process in autoclaved aerated concrete (AAC) formation. The system includes a novel autoclave cell for transmission XRD with thin beryllium windows, a two-dimensional photon-counting pixel array detector, and uses high energy X-rays from a synchrotron radiation source. The temperature and pressure inside the cell are extremely stable during hydrothermal reaction over the course of several hours. The system was utilized for the formation reaction of AAC. Phase evolution was clearly observed, including several intermediate phases, and detailed information on the structural changes during the hydrothermal reaction were obtained.

A new method, namely UACIEM, to extract reliable intensities of nonequivalent systematical overlapping reflections has been proposed and tested by simulated powder diffraction data from known crystal structures. Using both crystallographic and structural chemistry information, the method reconstructs diffraction intensities and solves a crystal structure through an iterative procedure. Our study shows that UACIEM is successful for cases where more than 30% of the total scattering power is located with precision from equivalent systematical overlapping reflections. The UACIEM process is not needed when equivalent systematical overlapping reflections are sufficient to reveal a crystal structure. UACIEM may fail in cases when: (i) only a small portion of the total scattering power (e.g., less than 7%) can be located, and (ii) most of the total scattering power (e.g., 95%) is located, but the atomic coordinates are not accurately known. The UACIEM method is superior to the simple equipartition methods for nonequivalent systematical overlapping reflections.

X-ray powder diffraction investigation of the new high temperature polymorphs beta- and gamma-CaTeO3 and gamma- and delta-CaTe2O5 and picnometric measurements of the room temperature phases of the two compounds have been carried out. The study led to the elucidation of their unit cell structures and assignment of entirely new lattice types and parameters to the room temperature phases of CaTeO3 and CaTe2O5 in contrast and supersession to the existing structural information. The results are as follows: CaTeO3 has only one stable phase at room temperature and temperatures up to 882 °C, i.e., α- and has a triclinic unit cell with a=4.132±0.003 Å, b=6.120±0.006 Å, c=12.836±0.013 Å, α=121.80°, β=99.72°, γ=97.26°. The first high temperature phase stable between 882 and 894 °C, i.e., β-CaTeO3, has a monoclinic lattice: a=20.577±0.007 Å, b=21.857±0.009 Å, c=4.111±0.002 Å, β=96.15°, while the next phase stable above 894 °C, i.e., γ-CaTeO3, has a hexagonal unit cell with parameters: a=14.015±0.0001 Å, c=9.783±0.001 Å, c/a=0.698. CaTe2O5 has one stable phase at temperatures up to 802 °C, i.e., α-CaTe2O5 with a monoclinic lattice and parameters: a=9.069±0.002 Å, b=25.175±0.007 Å, c=3.366±0.001 Å, β=98.29 °. The first high temperature phase stable in the range 802–845°, i.e., β-CaTe2O5, is monoclinic with unit cell parameters: a=4.146±0.001 Å, b=5.334±0.002 Å, c=6.105±0.002 Å, β=98.362 °; the next higher temperature phase stable over 845–857 °C, i.e., γ-CaTe2O5, has an orthorhombic unit cell with: a=8.638±0.001 Å, b=9.291±0.001 Å, c=7.862±0.001 Å and the highest temperature solid phase stable above 857 °C, i.e., δ-CaTe2O5 has a tetragonal unit cell with a=5.764±0.000 Å, c=32.074±0.020 Å, c/a=5.5637.