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Journal of Applied Crystallography Jun 2018The need for rapid data collection and studies of small sample volumes in the range of cubic millimetres are the main driving forces for the concept of a new...
The need for rapid data collection and studies of small sample volumes in the range of cubic millimetres are the main driving forces for the concept of a new high-throughput monochromatic diffraction instrument at the Heinz Maier-Leibnitz Zentrum (MLZ), Germany. A large region of reciprocal space will be accessed by a detector with sufficient dynamic range and microsecond time resolution, while allowing for a variety of complementary sample environments. The medium-resolution neutron powder diffraction option for 'energy research with neutrons' (ErwiN) at the high-flux FRM II neutron source at the MLZ is foreseen to meet future demand. ErwiN will address studies of energy-related systems and materials with respect to their structure and uniformity by means of bulk and spatially resolved neutron powder diffraction. A set of experimental options will be implemented, enabling time-resolved studies, rapid parametric measurements as a function of external parameters and studies of small samples using an adapted radial collimator. The proposed powder diffraction option ErwiN will bridge the gap in functionality between the high-resolution powder diffractometer SPODI and the time-of-flight diffractometers POWTEX and SAPHiR at the MLZ.
PubMed: 29896055
DOI: 10.1107/S1600576718004223 -
International Journal of Molecular... Jan 2022In this work, we report on the synthesis, in-depth crystal structure studies as well as optical and magnetic properties of newly synthesized heterometallic quaternary...
In this work, we report on the synthesis, in-depth crystal structure studies as well as optical and magnetic properties of newly synthesized heterometallic quaternary selenides of the EuLnCuSe composition. Crystal structures of the obtained compounds were refined by the derivative difference minimization (DDM) method from the powder X-ray diffraction data. The structures are found to belong to orthorhombic space groups (structure type BaMnS for EuLaCuSe and structure type EuCuS for EuLnCuSe, where Ln = Sm, Gd, Tb, Dy, Ho and Y) and (structure type KZrCuS for EuLnCuSe, where Ln = Tm, Yb and Lu). Space groups and were delimited based on the tolerance factor t', and vibrational spectroscopy additionally confirmed the formation of three structural types. With a decrease in the ionic radius of Ln in the reported structures, the distortion of the (LnCuSe) layers decreases, and a gradual formation of the more symmetric structure occurs in the sequence BaMnS → EuCuS → KZrCuS. According to magnetic studies, compounds EuLnCuSe (Ln = Tb, Dy, Ho and Tm) each exhibit ferrimagnetic properties with transition temperatures ranging from 4.7 to 6.3 K. A negative magnetization effect is observed for compound EuHoCuSe at temperatures below 4.8 K. The magnetic properties of the discussed selenides and isostructural sulfides were compared. The direct optical band gaps for EuLnCuSe, subtracted from the corresponding diffuse reflectance spectra, were found to be 1.87-2.09 eV. Deviation between experimental and calculated band gaps is ascribed to lower states of Eu in the crystal field of EuLnCuSe, while anomalous narrowing of the band gap of EuYbCuSe is explained by the low-lying charge-transfer state. Ab initio calculations of the crystal structures, elastic properties and phonon spectra of the reported compounds were performed.
Topics: Crystallography, X-Ray; Lanthanoid Series Elements; Models, Molecular; Molecular Structure; Organometallic Compounds; Powder Diffraction; Selenium; X-Ray Diffraction
PubMed: 35163428
DOI: 10.3390/ijms23031503 -
Data in Brief Apr 2020The data presented in this article are related to the formation of a novel layered perovskite oxide material, PrSrMnO, through a solid-state synthesis route. Here, we...
The data presented in this article are related to the formation of a novel layered perovskite oxide material, PrSrMnO, through a solid-state synthesis route. Here, we present the high-resolution neutron powder diffraction and the X-ray powder diffraction data at room temperature. The new perovskite material crystallizes in the orthorhombic symmetry. Interpretation of this data can be found in a research article titled "Insight of novel layered perovskite PrSrMn2O5+δ: A neutron powder diffraction study" (Shammya et ., 2019) [1].
PubMed: 32055661
DOI: 10.1016/j.dib.2020.105173 -
Acta Crystallographica Section B,... Dec 2023The magnetic structure of chromium arsenide CrAs is studied with neutron powder diffraction at ambient pressure in the temperature range 1.5-300 K as well as with...
The magnetic structure of chromium arsenide CrAs is studied with neutron powder diffraction at ambient pressure in the temperature range 1.5-300 K as well as with neutron single-crystal diffraction at 2 K and 0.12 GPa. The material undergoes an anti-isostructural phase transition at T = 267 K and atmospheric conditions, in which both orthorhombic phases have the same space-group symmetry (Pnma, Z = 4) but different distortions of the parent hexagonal structure of the NiAs type (P6/mmc, Z = 2). The magnetic structure below T is incommensurate with the propagation vector k = (0, 0, k). At ambient pressure, the component k decreases from k = 0.3807 (7) at 260 K to k = 0.3531 (6) at 50 K. Below this temperature, it is basically constant. With increasing pressure at 2 K, k is also constant within standard uncertainties [k = 0.353 (2)]. For the analysis of the magnetic structure, a group-theoretical approach based on the space group of the nuclear structure and its subgroups is used. To avoid falling into false minima in the refinements, a random search for magnetic moments in the models is implemented. In the literature, the magnetic structure has been determined on the basis of powder diffraction data as a double helix propagating along the c axis. Although this double-helical model leads to satisfactory agreement factors for our powder data, it does not reproduce the intensities of the magnetic satellite reflections measured on single-crystal data in a satisfactory way and can therefore be discarded. Instead, several other models are found that lead to better agreement. Each of them is spiral-like with directional components in all three directions and with no spin-density wave character that would cause a non-constant magnetic moment. In all these models, the ordering of the spins is neither a pure helix nor a pure cycloid. Instead, the unit vectors of the spin rotation planes make an angle α, 0° < α < 90°, with respect to the c* direction. The model in superspace group P2.1'(α0γ)0s yields the best agreement factors in the refinements of the neutron single-crystal and powder diffraction data. This model is unique as it is the only one in which all the magnetic moments rotate with the same chirality.
PubMed: 37820014
DOI: 10.1107/S205252062300817X -
Journal of Applied Crystallography Dec 2021A collection of scholarly scripts dealing with the mathematics and physics of peak profile functions in X-ray powder diffraction has been written using the Wolfram...
A collection of scholarly scripts dealing with the mathematics and physics of peak profile functions in X-ray powder diffraction has been written using the Wolfram language in . Common distribution functions, the concept of convolution in real and Fourier space, instrumental aberrations, and microstructural effects are visualized in an interactive manner and explained in detail. This paper is the first part of a series dealing with the mathematical description of powder diffraction patterns for teaching and education purposes.
PubMed: 34963769
DOI: 10.1107/S1600576721009183 -
Acta Crystallographica. Section E,... Apr 2017At a temperature of 100 K, CHN·I (), crystallizes in the monoclinic space group 2/. The formamidinium cation adopts a planar symmetrical structure [the r.m.s....
At a temperature of 100 K, CHN·I (), crystallizes in the monoclinic space group 2/. The formamidinium cation adopts a planar symmetrical structure [the r.m.s. deviation is 0.002 Å, and the C-N bond lengths are 1.301 (7) and 1.309 (8) Å]. The iodide anion does not lie within the cation plane, but deviates from it by 0.643 (10) Å. The cation and anion of form a tight ionic pair by a strong N-H⋯I hydrogen bond. In the crystal of , the tight ionic pairs form hydrogen-bonded zigzag-like chains propagating toward [20-1] strong N-H⋯I hydrogen bonds. The hydrogen-bonded chains are further packed in stacks along [100]. The thermal behaviour of was studied by different physicochemical methods (thermogravimetry, differential scanning calorimetry and powder diffraction). Differential scanning calorimetry revealed three narrow endothermic peaks at 346, 387 and 525 K, and one broad endothermic peak at ∼605 K. The first and second peaks are related to solid-solid phase transitions, while the third and fourth peaks are attributed to the melting and decomposition of . The enthalpies of the phase transitions at 346 and 387 K are estimated as 2.60 and 2.75 kJ mol, respectively. The X-ray powder diffraction data collected at different temperatures indicate the existence of as the monoclinic (100-346 K), ortho-rhom-bic (346-387 K) and cubic (387-525 K) polymorphic modifications.
PubMed: 28435723
DOI: 10.1107/S205698901700425X -
Acta Crystallographica. Section E,... Mar 2021The crystal structure of tribarium dicitrate penta-hydrate, [Ba(CHO)(HO)]·HO, has been solved and refined using synchrotron X-ray powder diffraction data, and optimized...
The crystal structure of tribarium dicitrate penta-hydrate, [Ba(CHO)(HO)]·HO, has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. The BaO and BaO coordination polyhedra share edges and corners to form a three-dimensional network. All of the active hydrogen atoms act as donors in O-H⋯O hydrogen bonds. Most of the acceptors are carboxyl-ate oxygen atoms, but there are also water⋯water hydrogen bonds. Both of the citrate hydroxyl groups form intra-molecular O-H⋯O hydrogen bonds to terminal carboxyl groups.
PubMed: 33953946
DOI: 10.1107/S2056989021001407 -
Frontiers in Chemistry 2022We herein describe an optimal approach for the efficient synthesis of -desmethylvenlafaxine succinate monohydrate (DVS) with high yield and high purity through 5-step...
We herein describe an optimal approach for the efficient synthesis of -desmethylvenlafaxine succinate monohydrate (DVS) with high yield and high purity through 5-step reactions, including benzyl protection of the phenolic hydroxyl group, cyclohexanone condensation, deprotection, cyano reduction, dimethylation, and succinic acid salt formation from -hydroxybenzene acetonitrile as a starting material. 4-Benzyloxyphenylacetonitrile (Intermediate I) was prepared by the hydroxyl protection of the bromide benzyl--hydroxyphenylacetonitrile catalyzed by potassium carbonate with 99.83% purity and 98.92% yields. The 1, 2-nucleophilic addition of intermediate I to cyclohexanone promoted by sodium hydroxide with the homogeneous catalyst (n-Bu)NBr to the preparation of 1-[Cyano(4-benzyloxyphenyl)methyl]cyclohexanol (Intermediate II) was obtained by 99.13% purity and 99.71% yields. Cyclohexanone residues and benzyl bromide residues were trace, and tetrabutylammonium bromide residues were UNDER 0.7 ppm, which further improves the residual standards for genotoxic impurities (GIs). 1-[2-amino-1-(4-hydroxyphenyl)ethyl]cyclohexanol hydrochloride (Intermediate III) was prepared by 10% palladium-carbon under 2.0 MPa up to 98.32% purity and 94.20% yields. -desmethylvenlafaxine (ODV) was synthesized by dimethylation of intermediate III with 37% formaldehyde solution and 85% formic acid solution. The highest purity was up to 99.20% and the yield was up to 84.77%. -desmethylvenlafaxine succinate monohydrate (DVS) was formed from succinic acid and -desmethylvenlafaxine (ODV) and crystallized in a mixed solvent of acetone and water (3:1) to obtain 99.92% purity and 90.27% yields. The 5-step total yields of desvenlafaxine succinate monohydrate is 71.09%, and its crystal form has characteristic peaks at 5, 10, 21, and 26 min by XRD powder diffraction, which is consistent with the crystalline form I. Compared with conventional synthesis strategy, we revealed a novel and green process with a high total yield, high atomic economy, low environmental pollution, high operational safety, and high residual standards for genotoxic impurities (GIs), which improves drug safety.
PubMed: 36059880
DOI: 10.3389/fchem.2022.860292 -
Powder Diffraction 2018This work provides a short summary of techniques for formally-correct handling of statistical uncertainties in Poisson-statistics dominated data, with emphasis on X-ray...
This work provides a short summary of techniques for formally-correct handling of statistical uncertainties in Poisson-statistics dominated data, with emphasis on X-ray powder diffraction patterns. Correct assignment of uncertainties for low counts is documented. Further, we describe a technique for adaptively rebinning such data sets to provide more uniform statistics across a pattern with a wide range of count rates, from a few (or no) counts in a background bin to on-peak regions with many counts. This permits better plotting of data and analysis of a smaller number of points in a fitting package, without significant degradation of the information content of the data set. Examples of the effect of this on a diffraction data set are given.
PubMed: 30996515
DOI: 10.1017/S0885715618000726 -
International Journal of Pharmaceutics:... Dec 2023Synchrotron radiation offers a host of advanced properties, surpassing conventional laboratory sources with its high brightness, tunable phonon energy, photon beam...
Synchrotron radiation offers a host of advanced properties, surpassing conventional laboratory sources with its high brightness, tunable phonon energy, photon beam coherence for advanced X-ray imaging, and a structured time profile, ideal for capturing dynamic atomic and molecular processes. However, these benefits come at the cost of operational complexity and expenses. Three decades ago, synchrotron radiation facilities, while technically open to all scientists, primarily served a limited community. Despite substantial accessibility improvements over the past two decades, synchrotron measurements still do not qualify as routine analyses. The intrinsic complexity of synchrotron science means experiments are pursued only when no alternatives suffice. In recent years, strides have been made in technology transfer offices, intermediate synchrotron-based analytical service companies, and the development of high-throughput synchrotron systems at various facilities, reshaping the perception of synchrotron science. This article investigates the practical application of synchrotron X-Ray Powder Diffraction (s-XRPD) techniques in pharmaceutical analysis. By utilizing concrete examples, we demonstrate how high-throughput systems have the potential to revolutionize s-XRPD applications in the pharmaceutical industry, rapidly generating XRPD patterns of comparable or superior quality to those obtained in state-of-the-art laboratory XRPD, all in less than 5 s. Additional cases featuring well-established pharmaceutical active ingredients (API) and excipients substantiate the concept of high throughput in pharmaceuticals, affirming data quality through structural refinements aligned with literature-derived unit cell parameters. Synchrotron data need not always be state-of-the-art to compete with lab-XRPD data. The key lies in ensuring user-friendliness, reproducibility, accessibility, cost-effectiveness, and the streamlined efforts associated with synchrotron instrumentation to remain highly competitive with their laboratory counterparts.
PubMed: 38146324
DOI: 10.1016/j.ijpx.2023.100221