Search results for "Powder diffraction"
showing 10 items of 243 documents
Luminescence properties of Tb3+:Y3Al5O12 nanocrystallites prepared by the sol–gel method
2004
Tb 3+ :YAG nanocrystalline powders have been prepared by the sol-gel route. Structure and morphology of the obtained materials have been studied. The average grain sizes have been determined by X-ray powder diffraction measurements. Photo- and cathodoluminescence spectra of the Tb 3+ :Y 3 Al 5 O 12 powders have been measured. It has been found that the samples at low concentration demonstrate emission ascribable to the 5 D 3 →F J and 5 D 4 → 7 F J transitions. In particular, the concentration dependence of the luminescence spectra and lifetimes have been investigated as a function of the YAG grains sizes. It has been shown that the cross-relaxation responsible for the quenching of the 5 D 3…
Crystal structure determination of 1-pentanol from low-temperature powder diffraction data by Patterson search methods
2005
5 pages.-- PACS: 61.66.Hq; 61.50.Lt
Crystal Data for Metal Cimetidine Isotiocionates: M(CM)2(NCS)2 (M = Co(II), Ni(II), Cu(II))
1992
AbstractMetal cimetidine isothiocyanates, M(C10H16SN6)2(NCS)2, where M = Co(II), Ni(II) and Cu(II), have been investigated by means of X-ray powder diffraction. Unit cell dimensions were determined from powder diffractometer data. Refined cell parameters (monoclinic with a primitive cell), powder data, calculated densities and Z value are presented.
Crystal Data for Complexes of Co(II) and Ni(II) Perchlorates with Mepirizole
1992
AbstractMetal mepirizole perchlorates, M(C11H14N4O2)3 (C104)2 where M = Co(II) and Ni(II) have been investigated by means of X-ray powder diffraction. Unit cell dimensions were determined by indexing programs from diffractometer data. Refined cell parameters (monoclinic with a C-centered cell), calculated density and Z values are presented.
Powder diffraction analysis of gemstone inclusions
2011
Gemstones are pieces of materials that once cut and polished are used as jewels or adornments. Gemstones may be single crystal (such as diamonds), polycrystalline (such as lapis lazuli), or amorphous (such as amber). In any case, gems may have inclusions that may yield a variety of optic effects. It is also important to unravel the crystal structure of the inclusion(s) in order to determine the origin of the gem and to help to understand their formation mechanism. Here, we expand the use of powder diffraction to identify crystalline inclusions in bulk gemstones highlighting Mo Kα radiation to penetrate within compact gems. Initially, rock crystal quartz with rutile needles was investigated …
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…