EXPO2013: a kit of tools for phasing crystal structures from powder data

Altomare, Angela; Cuocci, Corrado; Giacovazzo, Carmelo; Moliterni, Anna; Rizzi, Rosanna; Corriero, Nicola; Falcicchio, Aurelia

doi:10.1107/s0021889813013113

Cited by 809 publications

(646 citation statements)

References 31 publications

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“…1), distances in the same space are expressed using reciprocal lattice units (rlu). The large sets of the diffraction data collected by the detector have been reduced using the Binoculars package: this procedure enables a correct evaluation of the Bragg peak intensities and the meshing in the reciprocal space of each pixel of the 2D detector [24,25].…”

Section: Reciprocal Space Mapping Strategymentioning

confidence: 99%

Operando SXRD of E-ALD deposited sulphides ultra-thin films: Crystallite strain and size

Giaccherini

Russo

Carlà

et al. 2018

Applied Surface Science

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a b s t r a c tElectrochemical Atomic Layer Deposition (E-ALD), exploiting surface limited electrodeposition of atomic layers, can easily grow highly ordered ultra-thin films and 2D structures. Among other compounds Cu x Zn y S grown by means of E-ALD on Ag(111) has been found particularly suitable for the solar energy conversion due to its band gap (1.61 eV). However its growth seems to be characterized by a micrometric thread-like structure, probably overgrowing a smooth ultra-thin films. On this ground, a SXRD investigation has been performed, to address the open questions about the structure and the growth of Cu x Zn y S by means of E-ALD. The experiment shows a pseudo single crystal pattern as well as a powder pattern, confirming that part of the sample grows epitaxially on the Ag(111) substrate. The growth of the film was monitored by following the evolution of the Bragg peaks and Debye rings during the E-ALD steps. Breadth and profile analysis of the Bragg peaks lead to a qualitative interpretation of the growth mechanism. This study confirms that Zn lead to the growth of a strained Cu 2 S-like structure, while the growth of the thread-like structure is probably driven by the release of the stress from the epitaxial phase.

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Section: Reciprocal Space Mapping Strategymentioning

confidence: 99%

Operando SXRD of E-ALD deposited sulphides ultra-thin films: Crystallite strain and size

Giaccherini

Russo

Carlà

et al. 2018

Applied Surface Science

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“…All of the possible space groups were tested using the EXPO2014 package 17) for crystal structure determination. A promising structural model with a reliability (R) index 18) R F of 30.0% was successfully obtained for the space group I23 (noncentrosymmetric).…”

Section: Characterizationmentioning

confidence: 99%

Crystal structures and polymorphism of Sr4[Al6O12]SO4

Banno

Ichikawa

Takeda

et al. 2017

J. Ceram. Soc. Japan

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We investigated the crystal structures of high-and low-temperature phases in Sr 4 [Al 6 O 12 ]SO 4 , and their thermal behavior by high-temperature X-ray powder diffraction (Cu K¡ 1 ), differential thermal analysis, and temperature-dependent Raman spectroscopy. The crystal structure at 298 K was isomorphous with that of Ca 4 [Al 6 O 12 ]SO 4 (space group Pcc2 and Z = 4). The structural model at 573 K (space group I23 and Z = 2) was characterized by the positional disordering of oxygen atoms that form [SO 4 ] tetrahedra. The maximum-entropy method-based pattern fitting method was used to confirm the validity of these structural models, in which conventional structure bias caused by assuming intensity partitioning was minimized. The starting temperature of the cubic-to-orthorhombic transformation during cooling (= 524 K) was slightly higher than that of the reverse transformation during heating (= 519 K). The negative thermal hysteresis (= ¹5 K) strongly suggested the transformation being thermoelastic. At around the transformation temperature during heating, the vibrational spectra, corresponding to the Raman-active [SO 4 ] internal stretching mode, showed the continuous and gradual change in the slope of full width at half maximum versus temperature curve. This strongly suggests that the phase transformation would be principally accompanied by the statistical disordering of oxygen-atom positions, without distinct dynamical reorientation of the [SO 4 ] tetrahedra.

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“…45 The crystal structure was solved by a Simulated Annealing algorithm implemented in the program EXPO 2014. 46 Rietveld refinement 47 was performed using the program TOPAS Academic 4.1. 48 The background was modelled by a Chebyshev polynomial and the peak shape was modelled by a pseudo-Voigt function.…”

Section: Methodsmentioning

confidence: 99%

Investigation of an Amide-Pseudo Amide Hydrogen Bonding Motif within a Series of Theophylline:Amide Cocrystals

Eddleston

Arhangelskis

Fábián

et al. 2015

Crystal Growth & Design

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The pharmaceutically active compound theophylline (T) was cocrystallized with the amides formamide (1), acetamide (2), N-methylformamide (3), N,N-dimethylformamide (4), benzamide (5), and pyrazinamide (6), with systems T:1, T:5, and T:6 displaying polymorphic behavior. The cocrystals with formamide (T:1), acetamide (T:2), and benzamide (T:5), and one polymorph of the cocrystal with pyrazinamide (T:6-I), contain an R 2 2 (9) hydrogen bonding motif between the amide cocrystal formers and the HN−C−CO moiety of the theophylline molecule (an amide-pseudo amide synthon). This motif was, however, absent from the other polymorph of the pyrazinamide cocrystal (T:6-II) and also from the N-methylformamide cocrystal (T:3) (and is not possible in the N,N-dimethylformamide cocrystal (T:4)). These observations are rationalized using hydrogen bond propensity calculations, although limitations of using such calculations for predicting cocrystallization are noted. The amide-pseudo amide synthon is favored when theophylline cocrystallizes with both primary amides and with secondary amides which are locked in a cis configuration. On heating, all cocrystals were found to dissociate before melting due to loss of the amide, making stability to dissociation a more meaningful measure of cocrystal stability than melting point for these systems. On dissociation of the cocrystals, theophylline typically crystallizes as the commonly observed polymorph Form II. In the case of the acetamide cocrystal (T:2), however, the rarely observed metastable polymorph, Form V, crystallizes concomitantly with Form II suggesting that cocrystal dissociation on heating could be a strategy for identifying novel polymorphic forms of compounds.

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EXPO2013: a kit of tools for phasing crystal structures from powder data

Cited by 809 publications

References 31 publications

Operando SXRD of E-ALD deposited sulphides ultra-thin films: Crystallite strain and size

Operando SXRD of E-ALD deposited sulphides ultra-thin films: Crystallite strain and size

Crystal structures and polymorphism of Sr<sub>4</sub>[Al<sub>6</sub>O<sub>12</sub>]SO<sub>4</sub>

Investigation of an Amide-Pseudo Amide Hydrogen Bonding Motif within a Series of Theophylline:Amide Cocrystals

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