Search results for "Powder diffraction"
showing 10 items of 243 documents
Solution synthesis of nanoparticular binary transition metal antimonides
2011
The preparation of nanoengineered materials with controlled nanostructures, for example, with an anisotropic phase segregated structure or a regular periodicity rather than with a broad range of interparticle distances, has remained a synthetic challenge for intermetallics. Artificially structured materials, including multilayers, amorphous alloys, quasicrystals, metastable crystalline alloys, or granular metals, are mostly prepared using physical gas phase procedures. We report a novel, powerful solution-mediated approach for the formation of nanoparticular binary antimonides based on presynthesized antimony nanoparticles. The transition metal antimonides M-Sb (M = Co, Ni, Cu(2), Zn) were …
Phase formation in mixed TiO2-ZrO2 oxides prepared by sol-gel method
2011
Pure titania, zirconia, and mixed oxides (3—37 mol.% of ZrO2) are prepared using the sol-gel method and calcined at different temperatures. The calcined samples are characterized by Raman spectroscopy, X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption porosimetry. Measurements reveal a thermal stability of the titania anatase phase that slightly increases in the presence of 3—13 mol.% of zirconia. Practically, the titania anatase-rutile phase transformation is hindered during the temperature increase above 700 C. The mixed oxide with 37 mol.% of ZrO2 treated at 550 C shows a new single amorphous phase with a surface area of the…
"Identification of mixed bromidochloridotellurate anions in disordered crystal structures of (bdmim)2[TeX2Y4] (X, Y = Br, Cl; bdmim = 1-butyl-2,3-dim…
2013
Abstract The discrete mixed [TeBrxCl6−x]2− anions in their disordered crystal structures have been identified by using the phases prepared by the reaction of 1-butyl-2,3-dimethylimidazolium halogenides (bdmim)X with tellurium tetrahalogenides TeX4 (X = Cl, Br) as examples. Homoleptic (bdmim)2[TeX6] [X = Cl (1), Br (2)] and mixed (bdmim)2[TeBr2Cl4] (3), and (bdmim)2[TeBr4Cl2] (4) are formed depending on the choice of the reagents, and their crystal structures have been determined by single-crystal X-ray diffraction. The coordination environments of tellurium in all hexahalogenidotellurates are almost octahedral. Because of the crystallographic disorder, the mixed [TeBr2Cl4]2− and [TeBr4Cl2]2…
A biocompatible ZnNa2-based metal–organic framework with high ibuprofen, nitric oxide and metal uptake capacity
2020
Metal organic frameworks (MOFs) have received significant attention in recent years in the areas of biomedical and environmental applications. Among them, mixed metal MOFs, although promising, are relatively few in number in comparison with their homometallic analogues. The employment of benzophenone-4,4′-dicarboxylic acid (bphdcH2) in mixed metal MOF chemistry provided access to a 3D MOF, [Na2Zn(bphdc)2(DMF)2]n (NUIG1). NUIG1 displays a new topology and is a rare example of a mixed metal MOF based on 1D rod secondary building units. UV-vis, HPLC, TGA, XRPD, solid state NMR and computational studies indicated that NUIG1 exhibits an exceptionally high Ibuprofen (Ibu) and nitric oxide adsorpt…
Mesoporous iron phosphate/phosphonate hybrid materials
2014
Abstract Relatively high surface area pure mesoporous iron-phosphorus oxide-based derivatives have been synthesized through an S + I − surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from iron atrane complexes and phosphoric and phosphonic acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from iron phosphate up to hybrids involving approximately 30% of organophosphorus entities (phosphonates or diphosphonates). X-ray powder diffraction, transmission elect…
A cyano-bridged bimetallic ferrimagnet: Synthesis, X-ray structure and magnetic study
2010
Mixing of trans-[Mn(cyclam)Cl2]Cl (cyclam = 1,4,8,11-tetraazacyclotetradecane) and potassium hexacyanochromate (K3[Cr(CN)6]) aqueous solutions instantaneously yields a 1D infinite chain complex {[Mn(cyclam)(l-CN)2Cr(CN)4]� H2O}n (1). The crystal structure of 1, crystallizing in the monoclinic system with space group P21/n has been solved from X-ray powder diffraction data following direct space approach and refined by the Rietveld method. The structure analysis of 1 reveals alternating [Cr(CN)6] 3� and [Mn(cyclam)] 3+
Synthesis and structural and ionic conductivity studies of Na2ZrSi4O11
1996
The compound Na 2 ZrSi 4 O 1 1 has been prepared both by solid state synthesis and by the sol-gel technique via alkoxides. The structure of Na 2 ZrSi 4 O 11 was investigated by the Rietveld method using X-ray diffractometer data. The powder diffraction data show evidence for a triclinic distortion of the basic monoclinic structure. The ionic conductivity has been determined in the temperature interval 130-560°C using a.c. impedance measurements. The Na + ion mobility is limited, with E a =1.04 eV and σ(300°C)= 2-9 10 7 S/cm. Samples with Ta partially substituted for Zr, according to the formula Na 2-x (Zr 1-x Ta x )Si 4 O 11 with x ≤0.2, showed the same evidence for a triclinic distortion. …
MZ-35, a new layered pentasil borosilicate synthesized in the presence of large alkali cations
2013
Abstract A new layered borosilicate has been synthesized in the presence of cesium and sodium cations and its structure has been solved by a combination of automated diffraction tomography (ADT) and X-ray powder diffraction (XRPD). MZ-35 has a composition NaCs 2 [BSi 7 O 16 (OH) 2 ](OH) 2 ·4H 2 O and features space group P-4m2. The unusually small unit cell ( a 7.3081 A, c 10.7520 A) is shared by two random-stacked configurations of the structure: a network of connected pentasil units related to the layer of RUB-18 and a bidimensional checkerboard of intersecting ladders of 4-membered rings. The two configurations are related by the simple face-sharing inversion of a hydroxyl-bearing tetrah…
Pimobendan B from powder diffraction data
2013
The title molecule, C19H18N4O2{systematic name: (RS)-6-[2-(4-methoxyphenyl)-1H-benzimidazol-5-yl]-5-methyl-4,5-dihydropyridazin-3(2H)-one}, adopts an extended conformation. The dihedral angles between the central benzimidazole ring sytem and the pendant methoxyphenyl and pyridazinone residues are 1.41 (18) and 9.7 (3)°, respectively. In the crystal, N—H...N hydrogen bonds link the imadazole groups into [001] chains, and pairs of N—H...O hydrogen bonds link the pyridazinone groups into dimers. Together, these generate a two-dimensional supramolecular structure parallel to (010). The layers are linked by C—H...π interactions.
Naphthalene-containing polyamines supported in nanosized boehmite particles
2007
Boehmite nanoparticles with covalently linked polyamine chains functionalized with naphthalene fluorophores have been prepared and characterized. The characterization of the materials by elemental microanalysis, X-ray powder diffraction, MAS 29Si NMR and electron microscopy unambiguously prove that the covalent anchorage had occurred. Steady-state fluorescence emission studies show that the luminescent properties of the modified nanoparticles are sensitive to changes in concentration of hydrogen ions, metal ions and anionic nucleotides such as ATP. The behaviour of the attached materials in aqueous solution is parallel to the behaviour of the single fluorophoric polyamines. Comparisons are …