Search results for "powder"
showing 10 items of 437 documents
X-ray powder diffraction pattern for glucopyranosylsorbitol and glucopyranosylmannitol dihydrate
1997
X-ray powder data are given for glucopyranosylsorbitol, C12H24O11, and glucopyranosylmannitol dihydrate, C12H24O11 * 2H2O. Refined unit cell parameters for glucopyranosylsorbitol are: a=0.9124(4) nm, b=1.1336(5) nm, c=0.7232(3) nm, and β=91.23(4)° in space group P21 and those for glucopyranosylmannitol dihydrate are a=2.2579(15) nm, b=1.0016(5) nm, and c=0.7584(5) nm in space group P212121.
X-ray powder diffraction of mineral pigments and medicines from the 17th century pharmacy (Spezieria) Santa Maria della Scala in Rome, Italy
2018
The pharmacy (spezieria) Santa Maria della Scala was founded in Rome by the Discalced Carmelites Order in the 17th century, and during the 18th and 19th centuries it became the official supplier of medicines for Vatican Popes. The laboratory and the cases of this spezieria still preserve glass jars with organic and inorganic materials, which were presumably used for medicine and artistic material preparation, whose composition is unknown to date. A research project was initiated with the aim to study the stored materials and the role that the pharmacy played in regional, national and international contexts. In this manuscript, the compounds were analysed through X-ray powder diffraction wit…
Disordered sodium alkoxides from powder data: crystal structures of sodium ethoxide, propoxide, butoxide and pentoxide, and some of their solvates
2021
The crystal structures of NaOEt, NaOPr, NaOBu and NaOAm (Am = amyl = pentyl) were determined from powder data. These compounds crystallize in an anti-PbO structure in the space groups P 21 m and P4/nmm. Additionally, solvates with the composition NaOEt·2EtOH, NaOPr·2PrOH, NaOiPr·5iPrOH and NaOtAm·tAmOH were synthesized, and their structures were determined from single crystals. They form interesting chain structures of different compositions and topologies.
Electron Diffraction Reinvestigation of CdCr<sub>2</sub>Se<sub>4</sub> and ZnCr<sub>2-x</sub>V<sub>x</su…
2013
Crystal structure of two spinel single crystals CdCr2Se4 and ZnCr2-xVxSe4 have been reinvestigated using automated electron diffraction tomography method with beam precession. 3D reciprocal space have been reconstructed base on recorded tilt series. For both samples crystal structure was refined and the cubic symmetry with space group Fd-3m was confirmed. No additional electron potential has been located beside occupied atom sites.
Crystal structure and microstructure of synthetic hexagonal magnesium–cobalt cordierite solid solutions (Mg2−2xCo2xAl4Si5O18)
2013
Co2+-containing cordierite glasses, of nominal compositions (Mg1−xCox)2Al4Si5O18(withx= 0, 0.2, 0.4, 0.6, 0.8 and 1), were prepared by melting colloidal gel precursors. After isothermal heating at 1273 K for around 28 h, a single-phase α-cordierite (high-temperature hexagonal polymorph) was synthesized. All materials were investigated using X-ray powder diffraction and field-emission scanning electron microscopy. The crystal structure and microstructure were determined from X-ray diffraction patterns. Rietveld refinement confirmed the formation of magnesium–cobalt cordierite solid solutions. The unit-cell volume increased with the increase of cobalt content in the starting glass. The crysta…
X-ray powder diffraction study of monoclinic V4+-ZrO2 solid solutions obtained from gels
2003
Abstract Rietveld refinement of six monoclinic V x Zr 1− x O 2 solid solutions, with x =0, 0.01, 0.02, 0.05, 0.075 and 0.1, prepared by heating dried gel precursors at 1300°C in air atmosphere, has been characterized using X-ray powder diffractometer data. The present results confirm that crystal structure of these solid solutions contain V 4+ (Zr 4+ ) cations surrounded by seven oxygens, four at a distance between 2.13 and 2.28 A (referred as to O(2) in the tetrahedrally coordinated oxygens) and other three at a distance between 2.03 and 2.20 A (denoted as O(1) in the triangularly coordinated oxygens). The trends in the lattice parameter variation of V x Zr 1− x O 2 solid solutions specime…
Structure determination of three polymorphs of xylazine from laboratory powder diffraction data
2014
The crystal structures of three xylazine hydrochloride [N-(2,6-dimethylphenyl)-5,6-dihydro-4H-1,3-thiaz-2-amine hydrochloride] polymorphsA,ZandXhave been solved from powder diffraction data and refined using Rietveld refinement. Data were obtained with Cu Kα radiation. All polymorphs were found to have structures withZ′ = 1 andZ= 4. All the structures determined contained strong hydrogen bonds between the amino groups and chloride anions. The crystal structures of formsAandXfeatured π–π stacking interactions.
Cerium effect on the phase structure, phase stability and redox properties of Ce-doped strontium ferrates
2006
Nanostructured perovskite-type Sr1−aCeaFeO3−x, (0⩽a<0.15) powders have been prepared by citrate–nitrate smoldering auto-combustion. Their phase structure and stability, surface and morphological properties, reduction behavior and interaction with oxygen have been investigated by X-ray Powder Diffraction combined with Rietveld Analysis, 57Fe Mossbauer and X-ray Photoelectron Spectroscopies, N2-adsorption method, Temperature Programmed Reduction and Oxidation experiments. Our results reveal that citrate–nitrate auto-combustion method is effective in obtaining single phase Sr1−aCeaFeO3−x. The Sr1−aCeaFeO3−x structure is cubic only for a⩾0.06, while for a<0.06 remains tetragonal. Moreover, for …
USE OF NATURAL PRODUCTS FOR THE CONTROL OF POWDERY MILDEW OF ROSE PLANTS
2007
PowDery mildew caused by Podosphaera pannosa (Wallr. Fr.) De Bary on roses in greenhouse cultivation is usually controlled by chemical products. Aiming to lower the use of chemical treatments, in vitro and in planta assays were carried out using some natural products. The inhibitory effect of essential oils extracted from oregano inflorescences (Origanum heracleoticum L.) and cloves (Syzygium aromaticum L. Merril et L.M. Perry), was evaluated by in vitro tests. Essential oil at 0.5, and 0.125 ml/L concentration was added to conidia suspension (8 x 105 conidia/ml). After 2, 4, 8, 12, 24 and 48 hours, 400 conidia for each treatment and control were evaluated and the germination percentage cal…
Synchrotron powder-diffraction study of the spin transition compound [Fe(bpp)2](NCS)2·2H2O and soft X-ray-induced structural phase conversion
2008
Abstract We have studied the high spin and low spin structural phases of the two-step spin transition compound [Fe(bpp) 2 ](NCS) 2 ·2H 2 O (bpp: 2,6-bis(pyrazol-3-yl)pyridine) of different sample history with X-ray synchrotron ( λ ∼ 0.32 A) powder diffraction at different temperatures as well as with usual X-ray ( λ ∼ 1.54 A) powder diffraction at room temperature by performing rapid repeated scans at regular intervals of time. A structural phase transition occurs only during the first step of the spin transition. Time dependent interconversions of the two crystallographic phases have been observed at room temperature for this material. The results indicate that a soft X-ray (Cu-K α )-ind…