A general expression is proposed for the peak profile produced by a system of simple-shape crystalline domains (sphere, cube, tetrahedron, octahedron) whose size is dispersed according to a gamma distribution. The analytical expression obtained is particularly suited to “on the fly” pattern simulation or profile fitting for nanocrystalline materials. An advantage of using the proposed profile expression is that it always corresponds to a physically meaningful, though a priori fixed, size distribution, whereas the traditionally employed Voigtian profiles can produce unphysical negative size distributions for certain combinations of profile parameters. The peak profile depends on the distribution mean and variance instead of the more common empirical parameters of peak width and shape.

Quantification of mixtures via the Rietveld method is generally restricted to crystalline phases for which structures are well known. Phases that have not been identified or fully characterized may be easily quantified as a group, along with any amorphous material in the sample, by the addition of an internal standard to the mixture. However, quantification of individual phases that have only partial or unknown structures is carried out less routinely. This paper presents methodology for quantification of such phases. It outlines the procedure for calibration of the method and gives detailed examples from both synthetic and mineralogical systems. While the method should, in principle, be generally applicable, its implementation in the TOPAS program from Bruker AXS is demonstrated here.

The technique of standard addition in combination with powder X-ray diffraction was used to identify and quantify the amount of Ln3+ segregating into secondary phases from Ln3+doped alkaline earth aluminates. Results indicate that Ln3+ ions are more soluble in CaAl2O4 than SrAl2O4 and BaAl2O4, with this being rationalized by the structural details of the A sites. These results indicate that the enhancement of the luminescence afterglow obtained by doping AAl2O4:Eu2+ samples with Ln3+ ions is a result of much lower doping levels than previously thought.

The structural models of three synthetic Al-substituted goethite specimens have been refined from the neutron data, including crystallographic determinations of the Al levels and H positions. The d-I data were calculated for the final models. A relationship between the c unit cell parameter and Al content has been extended to the entire goethite-diaspore solid-solution system, which makes the regression equation procedure simpler and more accurate. A second prospective H site could not be confirmed because of the quality of existing neutron data. However, it is hoped that a further neutron powder diffraction study of a synthetic, fully deuterated goethite material may allow the existence of the site to be demonstrated.

The crystal structure of La2SiO5 was refined from laboratory X-ray powder diffraction data (CuKα1) using the Rietveld method. The crystal structure is monoclinic (space group P21∕c,Z=4) with lattice dimensions a=0.93320(2) nm, b=0.75088(1) nm, c=0.70332(1) nm, β=108.679(1)°, and V=0.46687(1) nm3. The final reliability indices were Rwp=7.14%, RP=5.52%, and RB=3.83%. There are two La sites in the structural model, La1 and La2. La1 is ninefold coordinated to oxygen, forming a tricapped trigonal prism with a mean La1-O distance of 0.263 nm. The La2O7 coordination polyhedron is a distorted capped octahedron with a mean La2-O distance of 0.251 nm. The La1O9 polyhedra share faces and the La2O7 polyhedra share edges, forming two sets of sheets that alternate parallel to the (100) plane. These sheets are linked through SiO4 tetrahedra and non-silicon-bonded oxygen atoms to form a three-dimensional structure. This compound is isomorphous with the low-temperature (X1) phases of R2SiO5 (R=Y and Gd). The volumes of RO9 polyhedra steadily increase with increasing ionic radius of R, from Y3+ to Gd3+ to La3+, which causes substantial volumetric expansion of the crystals.

Detailed structural properties of La1−xBaxCoO3 (LBCO) have been investigated by means of X-ray powder diffraction and Rietveld analysis. A structural phase transformation from R3c to Pm3m at x=0.30–0.35 has been detected based on a comparison between the refinements of R3c and Pm3m. The Co–O bond length of the CoO6 octahedron expanded rapidly with increasing Ba content when x<0.1, and then it leveled off and kept constant at 0.1⩽x⩾0.35, where the Co–O–Co bond angle reaches 180°. The Co–O bond length expansion resumed with increasing Ba content beyond x=0.35.

Improved X-ray powder diffraction data for synthetic PdSn are reported. Powder diffraction data were collected with a laboratory X-ray source (CuKα) for Rietveld refinement. Refined crystallographic data for PdSn (orthorhombic, Pnma) are a=6.1388(4), b=3.89226(3), c=6.3377(4) Å, V=151.43(2) Å3, Z=4, and Dx=9.87 g∕cm3.

Amantadine hydrochloride, p-aminophenol hydrochloride, and methylamine hydrochloride, compounds often studied in pharmacology, were investigated by means of powder diffractometry. The chemical formula of the first compound is C10H17N HCl and crystallizes in the monoclinic system, space group C2∕c (15) with lattice parameters a=2.0279(6) nm, b=1.1171(2) nm, c=9.759(4) nm, and β=109.00(3)°. p-Aminophenol hydrochloride C6H7NO HCl crystallizes in the orthorhombic system, space group P222 with lattice parameters a=0.6619(2) nm, b=0.88461(2) nm, and c=0.6101(2) nm. Methylamine hydrochloride CH5N∙HCl crystallizes in the tetragonal system, space group P4∕nmm (129) with lattice parameters a=b=0.6068(1) nm and c=0.50689(8) nm.

Synchrotron X-ray powder diffraction (XRPD) data were collected for the silver(I)-aspartame complex [Ag(C14H17N2O5)]∙1∕2H2O. The complex was obtained from a stoichiometric mixture of aspartame (3-amino-N-(α-carboxyphenethyl)-succinamic acid N-methyl ester, C14H18N2O5), Na2CO3, and AgNO3. Indexing using Crysfire and Chekcell proposed an orthorhombic unit cell with space group P2221. The lattice parameters are a=12.4750(1) Å, b=21.60614(14) Å, and c=4.88888(9) Å.

X-ray powder diffraction data for a rhombohedral AlPt phase formed by self-propagating, high-temperature reactions of Al∕Pt bi-layer films are reported. Multilayer Al∕Pt thin film samples, reacted in air or vacuum, transformed into rhombohedral AlPt with space group R-3(148). Indexing and lattice parameter refinement of AlPt powders (generated from thin-film samples) yielded trigonal/hexagonal unit-cell lattice parameters of a=15.623(6) Å and c=5.305(2) Å, Z=39, and V=1121.5 Å3.

An incident beam X-ray collimator for Mao-Bell type diamond anvil cell (DAC) has been developed. Alignment of the collimator is carried out in situ while viewing the image of the collimated X-ray spot formed on a thin layer of fluorescent material spread on the diamond anvil culets with the help of a microscope. Special precaution has been taken to meet the radiation safety requirements during alignment and routine use. This collimator is of immense help for laboratory based high pressure X-ray diffraction experiments.

Thin-walled heat-shrink poly(ethylene terephthalate) (PET) tubing is reported for use as an alternative for glass and Kapton® capillaries. PET tubing displays properties such as low X-ray absorption and smooth diffraction profiles. The 2.0 mm thin-walled (0.05 mm thick) and 0.5 mm thin-walled (0.02 mm thick) heat-shrink PET capillaries are 86% and 96% transparent to 1.54 Å X-rays. The low X-ray absorption and relatively smooth X-ray scattering profile of PET make it an ideal material for the home laboratory where the long wavelength, low flux, and low brilliance X-ray sources are employed. PET capillaries can be easily cut and manipulated and fixed to copper pins, which in turn can be employed in low-temperature and automated data collection routines.