Gemstones are pieces of materials that once cut and polished are used as jewels or adornments. Gemstones may be single crystal (such as diamonds), polycrystalline (such as lapis lazuli), or amorphous (such as amber). In any case, gems may have inclusions that may yield a variety of optic effects. It is also important to unravel the crystal structure of the inclusion(s) in order to determine the origin of the gem and to help to understand their formation mechanism. Here, we expand the use of powder diffraction to identify crystalline inclusions in bulk gemstones highlighting Mo Kα radiation to penetrate within compact gems. Initially, rock crystal quartz with rutile needles was investigated and rutile diffraction peaks were more conspicuous in the Mo pattern than in the Cu pattern. Next, rock crystal quartz with beetle legs was characterized and the red iron oxide inclusion was identified as hematite. The study of a fake gem, glass showing aventurine effect, gave the diffraction peaks of metallic copper. Later, polycrystalline gems, moss agate, and aventurine quartz were also studied. The powder patterns of these compact gemstones could be successfully fitted using the Rietveld method. Finally, we discuss opportunities for further improvements in laboratory powder diffraction to characterize inclusions in compact gems.

The National Institute of Standards and Technology (NIST) certifies a suite of Standard Reference Materials (SRMs) to address specific aspects of the performance of X-ray powder diffraction instruments. This report describes SRM 1878b, the third generation of this powder diffraction SRM. SRM 1878b is intended for use in the preparation of calibration standards for the quantitative analyses of α-quartz by X-ray powder diffraction in accordance to National Institute for Occupational Safety and Health Analytical Method 7500, or equivalent. A unit of SRM 1878b consists of approximately 5 g of α-quartz powder bottled in an argon atmosphere. It is certified with respect to crystalline phase purity, or amorphous phase content, and lattice parameter. Neutron powder diffraction, both time of flight and constant wavelength, was used to certify the phase purity using SRM 676a as an internal standard. A NIST-built diffractometer, incorporating many advanced design features was used for certification measurements for lattice parameters.

The growing interest in the use of powder X-ray diffractometry for materials’ characterization has led to the introduction of relevant concepts (e.g. microstructure, strain, anisotropy, texture) to undergraduate teaching in engineering and science. In this concern, the study of polycrystalline materials underlays the use of appropriate software: free, licensed, proprietary, or commercial to assist research on structure determination, structure refinement, and microstructure characterization. Today with the easy access to personal computers, routines for powder diffractometry also becomes feasible to use for non-specialist. Therefore, it would be relevant that students with computing knowledge may decide to improve routines on such three tasks incorporating their own computational approaches. In this study, we show the development of a ready-to-use and open source program written in GNU-Octave (v4.2.1) focused on X-ray diffraction line-profile analysis. The programing language platform was chosen mainly because of two reasons: (1) there is no requirement for commercial licenses, meaning that both programing language and routines can be downloaded online, facilitating collaborative efforts between students, instructors, and developers, and (2) easy re-coding of evaluation strategies is always allowed through fast implementation of modules into the code. The code, IndexCub, features routines for background subtraction, whole profile smoothing, and Kα2 radiation removal, location of diffraction peaks positions, indexing for cubic specimens, multi peak separation of individual peaks, and evaluation of full-width at half-maximum and integral breadth values. Microstructure properties are characterized through the use of integral breadth methods (e.g. Williamson–Hall) and Fourier analysis (e.g. Warren–Averbach), and the anisotropy effects are incorporated introducing calculations of contrast factors. In terms of diffraction domain sizes, size distribution, and the lattice microstrain, the analysis of the microstructure is discussed along with examples for polycrystalline coarse-grained materials (NaCl), epitaxial film (Si), and thin-films (Au) specimens. The code facilitates the understanding of microstructure analysis by using theoretical approaches well established and in state-steady level.

Round and spiral-shaped coil springs enable various peening angles that correspond to the surface location, and the directional shot angles may lead to a nonuniform residual stress on the coil spring surface. It is commonly known that a material under directional deformation exhibits a nonlinear 2θ-sin2ψ diagram (ψ split) due to the triaxial stress state. In this study, the residual stress distributions of spring materials deformed by shot peening at different angles were measured, and the microstructure for carbide precipitates was examined using a field-emission scanning electron microscope (FE-SEM). The nonlinearity in the 2θ-sin2ψ diagram for the shot peening samples was revealed. The extent of the ψ split increased with increasing shot peening angles, and was dependent not only on the mass fraction of carbide particles but also on the size distribution of the carbide particles.

The diffraction patterns of coarse grained materials are compared to specimens with crystallite sizes of less than 1 µm characterized by diffraction spots. Based on an analysis of spot intensities it is shown that for: (a) an at-random distribution of crystallite orientations and (b) under the assumption of specific crystallite shapes it becomes possible to evaluate the distribution N(l) of linear crystallite dimensions (0.1 µm < l < 20 µm) from measured spot intensity distributions z(i).

Precise X-ray powder diffraction patterns of two isostructural triborates, CsB3O5(CBO) and TlB3O5(TBO), have been collected on a D5000 diffractometer with a primary monochromated beam (λ CuKα1=1.5406 Å). Refinement of indexed reflections in the space group P212121 led to: a=6.201(1) Å, b=8.514(2) Å, c=9.176(2) Å, Z=4, Dx=3.363 for CBO and a=5.2156(4) Å, b=8.2659(6) Å, c=10.2240(9) Å, Z=4, Dx=4.773 for TBO. The Smith–Snyder figures of merit are F30=53.0 (0.0101, 56) for CBO and F30=112.9 (0.0074, 36) for TBO. These values are much better than the previous ones published in Powder Diffraction File.

An experimental investigation has been carried out to determine the extent to which axial divergence in a conventional powder diffractometer influences the measurement of peak profile parameters. A Siemens D5000 θ–2θ diffractometer was used for this study along with the LaB6 line profile standard SRM 660. Eight unique levels of axial divergence were investigated either by removing one or more of the Soller slits, or by introducing different combinations of Soller slits in the incident and diffracted beams. The measure of axial divergence used throughout is based on the maximum axial divergences of the incident and diffracted beams, Ψi and Ψd. Axial divergence produces a small and almost constant shift δ2θp in the peak angle which in a typical diffractometer would amount to a zero offset 2θ≈0.005°. The integrated intensity of a profile increases almost linearly with the product Ψi*Ψd. The increase in breadth in profiles in the angular region 2θ<120° arises mainly from the change in asymmetry DH=Hlo−Hhi in which one side of the profile broadens (i.e., either the high angle or low angle side) without any significant broadening of the other side. Moreover, the asymmetry DH is linearly dependent on 2θ for a fixed level of axial divergence, and linearly dependent on the total axial divergence Ψi+Ψd at fixed 2θ.

X-ray powder diffraction data for a new phase of dicalcium silicate, x-Ca2SiO4, are reported. The sample was prepared by the dehydration of hydrothermally synthesized α-type dicalcium silicate hydrate, Ca2(SiO4H)OH, at a temperature of 800 °C. Crystallographic data were Ca2SiO4, monoclinic, P21/c (No. 14), a=8.2127(5), b=9.7930(4), c=9.7954(5) Å, β=94.848(5)°, V=785.00(7) Å3, Z=8, and Dx=2.91 g·cm−3.

An indexed X-ray powder diffraction pattern is reported for Ca4A6O12SO4, prepared by solid state reaction. The compound crystallizes in the tetragonal system with a = 13.031(3) and c = 9.164(2) Å, V = 1556.1 (8) Å3, Z = 4.

Based on analysis of its powder diffraction pattern, tetracycline hydrochloride is orthorhombic; the space group is probably P212121(19) or P21212(18). Indexed powder data and refined cell parameters are presented.

X-ray powder diffraction data for Bi2Mo3O12·nH2O (n = 4.75) were obtained. The crystal system was determined to be monoclinic with space group P21or P21/m. The unit cell parameters were refined to a = 6.334(2) Å, b = 11.593(2) Å, c = 5.777(2) Å, and β= 113.166(8)°.

Observed and calculated X-ray powder diffraction data are reported for ZnGa2S4. After corrections to the observed data, refined tetragonal unit cell parameters ao= 5.2779(2), co= 10.4179(8) Å (λ = 1.54051 Å) were obtained. The powder pattern for ZnGa2S4was calculated in space group Iwith a stoichiometric amount of Zn and Ga randomly distributed amongst the two cation sites.

The new heteropoly blue compound (MoO2)0.5PMo14O42, which is relevant in the context of catalytic activity of heteropoly-molybdates, was prepared by controlled thermolysis of (NH4)3PMo12O40 at 730 K in a nitrogen atmosphere. Powder X-ray diffraction analysis showed that this compound has a cubic unit cell, space group Pn3m (No. 224), with ao=11.795(2) Å, Z=2 and DXR=4.2466 g cm−3. Computer modeling and Rietveld analysis of powder diffraction patterns led to a proposed structure of the corresponding Keggin-cage unit PMo14O42.

The structure of the anticancer drug carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, C5H9Cl2N3O2) was successfully determined from laboratory X-ray powder diffraction data recorded at 278 K and at 153 K. Carmustine crystallizes in the orthorhombic space group P212121 with Z = 4. The lattice parameters are a = 19.6935(2) Å, b = 9.8338(14) Å, c = 4.63542(6) Å, V = 897.71(2) ų at 153 K, and a = 19.8522(2) Å, b = 9.8843(15) Å, c = 4.69793(6) Å, V = 921.85(2) ų at 278 K. The Rietveld fits are very good, with low R-values and smooth difference curves of calculated and experimental powder data. The molecules form a one-dimensional hydrogen bond pattern. At room temperature, the investigated commercial sample of carmustine was amorphous.

X-ray powder diffraction data, unit-cell parameters, and space group for loratadine (C22H23ClN2O2) are reported [a = 28.302(18) Å, b = 4.996(3) Å, c = 29.154(19) Å, β = 109.158(2)°, unit-cell volume V = 3894.25 Å3, Z = 8, and space group C2/c]. All measured lines were indexed and are consistent with the C2/c space group. No detectable impurities were observed.

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.

In this investigation, the ability of Rietveld refinement method was used to simultaneously refine the structure and microstructure and evaluate the linear defects of cubic crystals. To do this, the basis of Stephans theory, about the anisotropic strain broadening, was developed and the values of dislocation density as well as the fraction of dislocation types were estimated. The reliability of this procedure was checked by selecting four different nanocrystaslline samples and evaluating the microstructure of these materials. Finally, the results were compared with those extracted from the whole powder pattern modeling method. Good agreement was achieved between the results of two methods.

Particulate matter (PM) specimens from a traffic site were sampled on Teflon filters using a low volume sampler. The sampling campaign ran over a one-year period with sampling frequency of twice a week for both PM2.5 and PM10. X-ray diffraction (XRD) methods, which are not commonly used in PM analysis, have been utilized successfully to identify crystalline phases present, including secondary pollutants. XRD data confirmed results obtained by X-ray fluorescence, positive matrix factorization modeling, and scanning electron microscopy. PM2.5 consisted mainly of secondary sulfates, like Mascagnite [(NH4)2SO4], Koktaite [(NH4)2Ca(SO4)2·H2O], and Gypsum [CaSO4·2H2O]. For PM10, it was found that the major phases are mostly originating from natural sources, such as dust storms and sea salts, in addition to secondary compounds, such as sodium nitrate. The main phases identified were Calcite, Quartz, Gypsum, Halite, and Palygorskite.

In this work, SnS1−xSex ternary nanobelts were synthesized by a facile hydrothermal method without the assistance of surfactants. The structure, morphology, microstructure, compositions, chemical valences, phonon modes, and optical band gaps of the SnS1−xSex nanobelts were characterized in detail. The results indicate that the SnS1−xSex nanobelts have uniform one-dimensional morphology and are single crystals with high crystallinity. Se is incorporated into the SnS lattice to substitute for S-forming ternary SnS1−xSex alloy. With the increase of Se doping concentration, the optical band gaps of the nanobelts gradually decrease from 1.15 to 1.01 eV, confirming the tunable optical property achieved here.

The structural parameters of a second low-temperature form of KZnPO4 have been refined using Rietveld analysis of X-ray powder diffraction (XRPD) data. This form of KZnPO4 is isostructural with NH4ZnPO4I and has previously been denoted as KZnPO4II. This article uses the notation δ-KZnPO4, to be consistent with the α, β, and γ notation commonly used for other KZnPO4 phases.