Publications by authors named "Robert J Koch"

Data reduction and correction steps and processed data reproducibility in the emerging single-crystal total-scattering-based technique of three-dimensional differential atomic pair distribution function (3D-ΔPDF) analysis are explored. All steps from sample measurement to data processing are outlined using a crystal of CuIrS as an example, studied in a setup equipped with a high-energy X-ray beam and a flat-panel area detector. Computational overhead as pertains to data sampling and the associated data-processing steps is also discussed.

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A new family of layered alkali uranyl borates, A(UO)BO (A = Cs, Rb, K), was synthesized as high quality single crystals via high temperature flux growth methods. At room temperature, the compounds are structurally closely related although they crystallize in different monoclinic space groups, specifically 2/ (Cs), 2/ (Rb), and 2/ (K). At a low temperature (100 K), Cs(UO)BO becomes isostructural with K(UO)BO as the result of a reversible structure transition by Cs(UO)BO.

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Thermodynamic studies of actinide-containing metal-organic frameworks (An-MOFs), reported herein for the first time, are a step toward addressing challenges related to effective nuclear waste administration. In addition to An-MOF thermochemistry, enthalpies of formation were determined for the organic linkers, 2,2'-dimethylbiphenyl-4,4'-dicarboxylic acid (HMeBPDC) and biphenyl-4,4'-dicarboxylic acid (HBPDC), which are commonly used building blocks for MOF preparation. The electronic structure of the first example of An-MOF with mixed-metal AnAn'-nodes was influenced through coordination of transition metals as shown by the density of states near the Fermi edge, changes in the Tauc plot, conductivity measurements, and theoretical calculations.

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Atomic pair distribution (PDF) analysis has proven to be an exceptionally robust tool for probing the structure of amorphous, crystalline and crystallographically challenged materials. This issue of features a significant step forward in X-ray PDF methodology for thin films, with substantial improvements in both sensitivity and time resolution.

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