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71.
Investigation of Solid Complexes of Triphenylmethyl Salts with Donors Triphenylmethyl salts form crystalline complexes, which can be characterized by UV-VIS reflexion spectroscopy as well as by thermal methods. The stability of the solid complexes is essentially determined by the size of the substituents in the cation (p-R-C6H4)3C+ with R = CH3, H, Br and by that of the aromate (benzene, toluene, p-xylene, mesitylene). In constrat to the behaviour in solution a change of the anion (SbCl6−, FeCl4−) has a strong influence on the stability. Because of the appearance of a charge-transfer absorption the complexes are described as EDA complexes. 相似文献
72.
R. Mitdank D. HabelO. Görke M. HarthH. Schubert H. Winter 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(3):345-352
TiO2/V2O5 based ceramic materials applied in catalysis were investigated. Structural properties like the grain diameter of these pressed ceramic powders were analysed by means of Rutherford backscattering (RBS) making use of an analytic model to describe the energy spectra of porous rough samples. Grain diameters of these samples were deduced as function of process temperature and chemical composition and related to a phase transition from the TiO2-Anatase/V2O5-Shcherbinaite to Rutile solid solution (Rutile-ss) structure. RBS data were compared to results of scanning electron microscopy (SEM). The activation energy for the sintering at the phase transition was estimated to 5.4 eV. 相似文献
73.
Artur Glavic Jörg VoigtJörg Persson Yixi SuJürgen Schubert Joost de GrootWilli Zande Thomas Brückel 《Journal of Alloys and Compounds》2011,509(16):5061-5063
High quality thin films of TbMnO3 were grown by pulsed laser deposition on orthorhombicYAlO3 (1 0 0). The interface and surface roughness of a 55 nm thick film were probed by X-ray reflectometry and atomic force microscopy, yielding a roughness of 1 nm. X-ray diffraction revealed untwinned films and a small mosaic spread of 0.04° and 0.2° for out-of-plane and in-plane reflections, respectively. This high degree of epitaxy was also confirmed by Rutherford backscattering spectrometry. Using polarized neutron diffraction we could identify a magnetic structure with the propagation vector (0 0.27 0), identical to the bulk magnetic structure of TbMnO3. 相似文献
74.
D. Habel O. Görke M. Tovar M. Willinger M. Ziemann O. Schwarz R. Schomäcker H. Schubert 《Journal of the European Ceramic Society》2009,29(6):1093-1099
Commonly used catalysts in industry are compositions of highly dispersed particles. Typical systems consist of precious metals or transition metal oxides like V2O5 on oxide supports, especially TiO2, Al2O3 and SiO2. Support and active compound show a different chemical and material behaviour. A very important influence of the support on the active compound is the formation of microstrains due to the different thermal expansion behaviour. On the surface of a stiff linear elastic support the active compound is certainly strain hindered. In order to monitor the development of strain hindrance and further effects, in situ experiments were carried out at temperature both in an X-ray and in a neutron powder diffractometer. The width of the reflexes indicated a strong influence of the thermal expansion mismatch on peak width. The strain hindrance creates mismatch stresses high enough to overcome the yield stress of V2O5. The Williamson–Hall plots showed both a particle size effect as well as a stress widening but the measurements were difficult because of the materials anisotropy. The TEM work showed again very fine particles which agrees with the X-ray measurements. The support effect may be seen as thermal stress induced formation of a mosaic structure in the active compound. Moreover, the peak width correlated with the catalytic activity. The low ordered regimes in the mosaic structure are acting as further active centres for the catalytic reaction. 相似文献
75.
Continuous salt precipitation and separation from supercritical water. Part 2. Type 2 salts and mixtures of two salts 总被引:1,自引:0,他引:1
Martin Schubert 《The Journal of Supercritical Fluids》2010,52(1):113-11727
Using a continuously operated laboratory plant for the catalytic hydrothermal gasification of biomass featuring a supercritical water salt separator we investigated the separation performance of three different binary type 2 salt-water mixtures and three ternary salt-water mixtures that consisted either of two type 1 salts or two type 2 salts dissolved in water. It turned out that a concentrated salt brine could not be recovered at the salt separator for the binary type 2 salt-water mixtures of Na2CO3, Na2SO4, and K2SO4. These salts precipitate as solids from supercritical water and thus lead to salt deposits inside the salt separator vessel.The ternary mixtures of two type 1 salts dissolved in water (KH2PO4-K2HPO4-H2O and three different mixtures of NaNO3-K2CO3-water) exhibited a separation performance similar to the binary solutions of type 1 salts that were discussed in Part 1 of this article. However, the mixtures showed separation performances that were different from the corresponding single salt solutions.It was also possible to recover a concentrated brine when feeding solutions containing the two type 2 salts Na2CO3 and K2SO4. For these mixtures a certain amount of the type 1 salt K2CO3 might form in supercritical water leading to salt separation efficiencies up to 95% for these mixtures. 相似文献
76.
Challenges and Progress in High‐Throughput Screening of Polymer Mechanical Properties by Indentation
Johannes M. Kranenburg Catherine A. Tweedie Krystyn J. van Vliet Ulrich S. Schubert 《Advanced materials (Deerfield Beach, Fla.)》2009,21(35):3551-3561
Depth‐sensing or instrumented indentation is an experimental characterization approach well‐suited for high‐throughput investigation of mechanical properties of polymeric materials. This is due to both the precision of force and displacement, and to the small material volumes required for quantitative analysis. Recently, considerable progress in the throughput (number of distinct material samples analyzed per unit time) of indentation experiments has been achieved, particularly for studies of elastic properties. Future challenges include improving the agreement between various macroscopic properties (elastic modulus, creep compliance, loss tangent, onset of nonlinear elasticity, energy dissipation, etc.) and their counterpart properties obtained by indentation. Sample preparation constitutes a major factor for both the accuracy of the results and the speed and efficiency of experimental throughput. It is important to appreciate how this processing step may influence the mechanical properties, in particular the onset of nonlinear elastic or plastic deformation, and how the processing may affect the agreement between the indentation results and their macroscopic analogues. 相似文献
77.
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79.
Density functional theory along with a dielectric continuum solvation model has been applied to identify possible reaction intermediates for the catalytic hydrogenation of HCO3− anion into HCO2− that occurs in aqueous solutions in the presence of water-soluble ruthenium complexes. Bicarbonate ion is shown to coordinate to a Ru-dihydride species, which then undergoes a protonation process that yields a CO2 complex. The CH bond formation is found to take place via CO2 insertion into a RuH bond and the direct elimination of the formate product is shown to be an energetically favored step, which is assisted by the water medium. We find that water is directly involved in the reaction as a protonating/deprotonating agent and also acts as a coordinating ligand. 相似文献
80.
JD Anderson G Schubert RA Jacobson EL Lau WB Moore WL Sjogren 《Canadian Metallurgical Quarterly》1998,281(5385):2019-2022
Radio Doppler data from four encounters of the Galileo spacecraft with the jovian moon Europa have been used to refine models of Europa's interior. Europa is most likely differentiated into a metallic core surrounded by a rock mantle and a water ice-liquid outer shell, but the data cannot eliminate the possibility of a uniform mixture of dense silicate and metal beneath the water ice-liquid shell. The size of a metallic core is uncertain because of its unknown composition, but it could be as large as about 50 percent of Europa's radius. The thickness of Europa's outer shell of water ice-liquid must lie in the range of about 80 to 170 kilometers. 相似文献