A total pattern analysis suite of programs has been developed and incorporated into the ICDD® PDF-4 database. While the suite of programs is intended for the analysis of any diffraction pattern, particular attention was focused on the analysis of common amorphous, non-crystalline, or partially crystalline materials found in minerals, polymers, and pharmaceuticals. The suite of programs directly interfaces to the ICDD database and libraries of non-crystalline references.

Residual strain in electrodeposited Li films may affect safety and performance in Li metal battery anodes, so it is important to understand how to detect residual strain in electrodeposited Li and the conditions under which it arises. To explore this Li films, electrodeposited onto Cu metal substrates, were prepared under an applied pressure of either 10 or 1000 kPa and subsequently tested for the presence or absence of residual strain via sin2(ψ) analysis. X-ray diffraction (XRD) analysis of Li films required preparation and examination within an inert environment; hence, a Be-dome sample holder was employed during XRD characterization. Results show that the Li film grown under 1000 kPa displayed a detectable presence of in-plane compressive strain (−0.066%), whereas the Li film grown under 10 kPa displayed no detectable in-plane strain. The underlying Cu substrate revealed an in-plane residual strain near zero. Texture analysis via pole figure determination was also performed for both Li and Cu and revealed a mild fiber texture for Li metal and a strong bi-axial texture of the Cu substrate. Experimental details concerning sample preparation, alignment, and analysis of the particularly air-sensitive Li films have also been detailed. This work shows that Li metal exhibits residual strain when electrodeposited under compressive stress and that XRD can be used to quantify that strain.

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.

As a producer of certified reference materials (CRMs), NIST faces high demand for Standard Reference Materials (SRMs). The demand is exacerbated by widespread misuse of CRMs. When should one use CRMs? When should one not use CRMs? Must labs always use NIST SRMs? How can labs demonstrate analytical capabilities for their accreditation scopes? Why so many questions? Standards developers, laboratory accreditors, and laboratory staff must be able to understand these topics with respect to quality systems in compliance with ISO/IEC 17025. They must calibrate and validate test methods and document traceability to the International System of Units (SI). Many people working in laboratory accreditation and under the umbrella of a quality system do not fully understand what these things are, let alone the language of chemical metrology. On average, they have little training in analytical chemistry, elemental analysis, and reference material development. It is hoped this paper will impress upon the reader the need for understanding how CRMs can be best used in the laboratory. This paper provides a brief background on the above problems and then looks at some of the support and reference information provided by NIST to metals and mining industries labs, commercial CRM producers, and accrediting bodies. The concepts and guidance apply broadly to chemical metrology and fundamental analytical chemistry. The paper includes examples (some from X-ray fluorescence spectrometry) to illustrate concepts.

One challenge impeding the analysis of terabyte scale X-ray scattering data from the Linac Coherent Light Source (LCLS) is determining the number of clusters required for the execution of traditional clustering algorithms. Here, we demonstrate that the previous work using bi-cross validation to determine the number of singular vectors directly maps to the spectral clustering problem of estimating both the number of clusters and hyperparameter values. Applying this method to LCLS X-ray scattering data enables the identification of dropped shots without manually setting boundaries on detector fluence and provides a path toward identifying rare and anomalous events.

Tooth enamel, the outermost layer of human teeth, is a complex, hierarchically structured biocomposite. The details of this structure are important in multiple human health contexts, from understanding the progression of dental caries (tooth decay) to understanding the process of amelogenesis and related developmental defects. Enamel is composed primarily of long, nanoscale crystallites of hydroxyapatite that are bundled by the thousands to form micron-scale rods. Studies with transmission electron microscopy show the relationships between small groups of crystallites and X-ray diffraction characterize averages over many rods, but the direct measurement of variations in local crystallographic structure across and between enamel rods has been missing. Here, we describe a synchrotron X-ray-based experimental approach and a novel analysis method developed to address this gap in knowledge. A ~500-nm-wide beam of monochromatic X-rays in conjunction with a sample section only 1 μm in thickness enables 2D diffraction patterns to be collected from small well-separated volumes within the enamel microstructure but still probes enough crystallites (~300 per pattern) to extract population-level statistics on crystallographic features like lattice parameter, crystallite size, and orientation distributions. Furthermore, the development of a quantitative metric to characterize relative order and disorder based on the azimuthal autocorrelation of diffracted intensity enables these crystallographic measurements to be correlated with their location within the enamel microstructure (e.g., between rod and interrod regions). These methods represent a step forward in the characterization of human enamel and will elucidate the variation of the crystallographic structure across and between enamel rods for the first time.

X-ray powder diffraction data for new metal-organic compounds: tetrakis(3-ethylanilinium) octamolybdate Mo8O26(C8H12N)4 [a = 10.682(4), b = 16.589(5), c = 7.307(2) Å, α = 92.79(2)°, β = 97.99(3)°, γ = 103.89(3)°, V = 1240.27 Å3, Z = 1, space group P−1]; tetrakis(3-ethylanilinium) octamolybdate tetrahydrate Mo8O26(C8H12N)4·(H2O)4 [a = 18.801(7), b = 17.943(6), c = 7.334(3) Å, β = 98.50(5)°, V = 2446.99 Å3, Z = 2, space group P21/m] and bis(3-ethylanilinium) pentamolybdate Mo5O16(C8H12N)2 [a = 34.643(6), b = 5.5796(7), c = 14.200(3) Å, β = 96.20(2)°, V = 2728.69 Å3, Z = 4, space group I2/a] are reported in this paper. The investigated compounds were synthesized from molybdic acid and 3-ethylaniline in acidic solution. In the first two cases, we obtained octamolybdates, while the last compound crystallized as pentamolybdate.

The crystal structure of atazanavir has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Atazanavir crystallizes in space group P21 (#4) with a = 15.33545(7), b = 5.90396(3), c = 21.56949(13) Å, β = 96.2923(4)°, V = 1941.134(11) Å3, and Z = 2. Despite being labeled as “atazanavir sulfate”, the commercial reagent sample consisted of atazanavir free base. The structure consists of an array of extended-conformation molecules parallel to the ac-plane. Although the atazanavir molecule contains only four classical hydrogen bond donors, hydrogen bonding is, surprisingly, important to the crystal energy. Both intra- and intermolecular hydrogen bonds are significant. The hydroxyl group forms bifurcated intramolecular hydrogen bonds to a carbonyl oxygen atom and an amide nitrogen. Several amide nitrogens act as donors to the hydroxyl group and carbonyl oxygen atoms. An amide nitrogen acts as a donor to another amide nitrogen. Several methyl, methylene, methyne, and phenyl hydrogens participate in hydrogen bonds to carbonyl oxygens, an amide nitrogen, and the pyridine nitrogen. The powder pattern is included in the Powder Diffraction File™ as entry 00-065-1426.

The crystal structure of atorvastatin calcium trihydrate (ACT) has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. ACT crystallizes in space group P1 (#1) with a = 5.44731(4), b = 9.88858(16), c = 29.5925(10) Å, α = 95.859(3), β = 94.211(1), γ = 105.2790(1)°, V = 1521.277(10) Å3, and Z = 1. The most prominent feature of the crystal structure is a hydrophilic layer parallel to the ab-plane. The atorvastatin anions bond to each side of the hydrophilic layer, forming a triple layer. The calcium coordination is distorted octahedral, with the CaO6 coordination sphere being comprised of four carboxylate oxygens, one coordinated water molecule, and a hydroxyl group from one but not the second atorvastatin anion. Several O–H⋯O hydrogen bonds form a two-dimensional network parallel to the ab-plane. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™.

The crystal and molecular structure of fenspiride, a bronchodilator and anti-inflammatory drug, are reported. Fenspiride crystallizes in the monoclinic system, with two crystallographically independent molecules in the general position of the space group P21/n (No. 14) and Z = 8. Rietveld refined unit cell parameters are a = 11.52013(8) Å, b = 5.614091(31) Å, c = 44.1567(4) Å, α = 90°, β = 93.0885(6)°, γ = 90°, and V = 2851.69(4) Å3.