Silver behenate, a possible low‐angle diffraction standard, was characterized using the powder diffraction technique. Diffraction patterns obtained with 1.54 Å synchrotron and Cu Kα radiations showed thirteen regularly spaced (00l) peaks in the range 1.5–20.0°2θ. With the National Institute of Standards and Technology's standard reference material silicon as an internal standard, the long spacing of silver behenate was accurately determined from the profile‐fitted synchrotron diffraction peaks, with d001 = 58.380 (3) Å. This result was in agreement with that obtained from the Cu Kα pattern. The profile widths of the silver behenate peaks were found to be consistently larger than those of the silicon peaks, indicating significant line broadening for silver behenate. The average crystallite size along the long‐spacing direction of silver behenate was estimated using the Scherrer equation, giving Davg = 900 (50) Å. Because silver behenate has a large number of well defined diffraction peaks distributed evenly in the 1.5–20.0°2θ range, it is suitable for use as an angle‐calibration standard for low‐angle diffraction. However, care must be taken if silver behenate is to be used as a peak‐profile calibration standard because of line broadening.

The ICDD's Powder Diffraction File™ (PDF®) is a database of inorganic and organic diffraction data used for phase identification and materials characterization by powder diffraction. The PDF has been available for over 75 years and finds application in X-ray, synchrotron, electron, and neutron diffraction analyses. With entries based on powder and single crystal data, the PDF is the only crystallographic database where every entry is editorially reviewed and marked with a quality mark that alerts the user to the reliability/quality of the submitted data. The editorial processes of ICDD's quality management system are unique in that they are ISO 9001:2015 certified. Initially offered as text on paper cards and books, the PDF evolved to a computer-readable database in the 1960s and today is both computer and web accessible. With data mining and phase identification software available in PDF products, and the databases’ compatibility with vendor (third party) software, the 1 000 000+ published PDF entries serve a wide range of disciplines covering academic, industrial, and government laboratories. Details describing the content of database entries are presented to enhance the use of the PDF.

A novel Pt(II) terpyridine complex that has a nicotinamide moiety linked to the terpyridyl ligand has been synthesized in good yield and studied structurally and spectroscopically. The complex, [Pt(Nttpy)Cl](PF(6))(2) where Nttpy = 4'-(p-nicotinamide-N-methylphenyl)-2,2':6',2' '-terpyridine, is observed to be brightly luminescent in the solid state at room temperature and at 77 K. The complex exhibits reversible vapochromic behavior and crystallographic change in the presence of several volatile organic solvents. Upon exposure to methanol vapors, the complex changes color from red to orange, and a shift to higher energy is observed in the emission maximum with an increase in excited-state lifetime and emission intensity. The crystal and molecular structures of the orange and red forms, determined by single-crystal X-ray diffraction on the same single crystal, were found to be equivalent in the molecular sense and only modestly different in terms of packing. In both forms, the cationic Pt(II) complexes possess distorted square planar geometries. Analysis of the orange form's crystal packing reveals the presence of solvent molecules in lattice voids, Pt...Pt separations averaging 3.75 A and a zigzag arrangement between nearest neighbor Pt atoms, whereas the red form is devoid of solvent within the crystal lattice and contains complexes stacked with a nearly linear arrangement of Pt(II) ions having an average distance of 3.33 A. On the basis of the crystallographic data, it is evident that sorption of methanol vapor induces a change in intermolecular contacts and Pt...Pt interactions in going from red to orange. Disruption of the d(8)-d(8) metallophilic interactions consequently alters the emitting state from (3)[(d)sigma*-pi*(terpyridine)] that is formally a metal-metal-to-ligand charge transfer (MMLCT) state in the red form to one in which the HOMO corresponds to a more localized Pt(d) orbital in the red form ((3)MLCT).

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A task group of the JCPDS-International Center for Diffraction Data (ICDD) was established with the charge of investigating the use of silver behenate, CH 3 (CH 2 ) 2 oCOO-Ag, as a possible low-angle calibration standard for powder diffraction applications. Utilizing several data collection and analysis techniques, long-period spacing (JQOI) values with a range of 58.219-58.480 A were obtained. Using the same collected data and one data analysis refinement calculation method resulted in d m values with a range of 58.303-58.425 A. Data collected using a silicon internal standard and the same singular data analysis calculation method provided d^ values with a range of 58.363-58.381 A.

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In this paper, a PEO−clay(PVP) nanocomposite was designed and the nanocomposite film was produced. The film exhibits a low thermal expansion coefficient of ∼10 ppm/°C, which is similar to that of metals. The film also exhibits an unexpected high heat distortion temperature, which is much higher than the melting point of polyethylene oxide (PEO), as well as a much improved O2 barrier property, high stiffness, and high strength. The significant property improvements are related to the structure of the formed composite. In this composite, the clay crystal is first intercalated by polyvinyl pyrrolidone (PVP), which regulates the stacking of the clay sheets and forms a well-ordered intercalated clay crystal. This intercalated clay crystal directs the crystallization and crystal orientation of the PEO in the composite. The property change with the amount of clay added suggests that there is a critical clay loading of ∼10 vol % beyond which the polymer based composite exhibits superior properties.

Silver sulfide, Ag2S, is most commonly known as the tarnish that forms on silver surfaces due to the exposure of silver to hydrogen sulfide. The mineral acanthite is a monoclinic crystalline form of Ag2S that is stable to 176°C. Upon heating above 176°C, there is a phase conversion to a body-centered cubic (bcc) form referred to as argentite. Further heating above 586°C results in conversion of the bcc phase to a face-centered cubic (fcc) phase polymorph. Both high-temperature cubic phases are solid-state silver ion conductors. In situ high-temperature X-ray diffraction was used to better understand the polymorphs of Ag2S on heating. The existing powder diffraction file (PDF) entries for the high-temperature fcc polymorph are of questionable reliability, prompting a full Rietveld structure refinement of the bcc and fcc polymorphs. Rietveld analysis was useful to show that the silver atoms are largely disordered and can only be described by unreasonably large isotropic displacement parameters or split site models.