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111.
《Analytical letters》2012,45(10):769-776
Abstract A method is reported for the determination of Ni, Co, Bi, Al, V, Ti, Cu, Si, Pb, Cr, Mg, Sn, and Fe in molybdenum metal by optical emission spectrography. The procedure consists of dissolving the metal in HNO3 and HCl, evaporating to dryness, and igniting at 500–550°C to MoO3. The MoO3 is mixed with an equal weight of GeO2, which acts as an inert collector, and ignited at 700–750°C to volatilize the MoO3. This double ignition method concentrates the impurities on the GeO2 thereby placing the trace elements within the range of the spectrograph. The residue is excited in a d c are at 10 amps and the spectra are recorded on a photographic emulsion. 相似文献
112.
G.Attilio Ardizzoia S Brenna G LaMonica A Maspero N Masciocchi 《Journal of organometallic chemistry》2002,649(2):173-180
Three new molybdenum(0) complexes, [Mo(CO)3(Hpz)3] (1), [Mo(CO)2(Hpz)2(DMAD)2] (2), (DMAD=dimethyl acetylenedicarboxylate) and [Mo(CO)3(1-Me-imidazole)3] (3) were synthesized and characterized. Their activity and selectivity in alkyne cyclotrimerization and co-trimerization reactions was investigated. The molecular structures of 1 and 2 have been determined by unconventional powder and standard single-crystal diffraction methods, respectively. 1 consists of a pseudo-octahedral complex of C3 symmetry, with the ligands in fac disposition; complex 2, of idealized C2 symmetry, is obtained by substitution of one CO and one pyrazole in 1 by two DMAD ligands, and shows the rare trans configuration of π-bound acetylenic moieties. 相似文献
113.
The effects of adsorbed H on the Mo1−xRex(110), x=0, 0.05, 0.15, and 0.25, surfaces have been investigated using low-energy electron diffraction (LEED) and high-resolution electron energy loss spectroscopy (HREELS). For the x=0.15 alloy only, a c(2×2) LEED pattern is observed at a coverage Θ0.25 ML. A (2×2) pattern is observed for H coverages around Θ0.5 ML from surfaces with x=0, 0.05, and 0.15. Both c(2×2) and (2×2) patterns are attributed to reconstruction of the substrate. At higher coverages, a (1×1) pattern is observed. For the alloy surface with x=0.25, only a (1×1) pattern is obtained for all H coverages. Two H vibrations are observed in HREELS spectra for all Re concentrations, which shift to higher energies at intermediate coverages. Both peaks exhibit an isotopic shift, confirming their assignment to hydrogen. For Re concentrations of x=0.15 and higher, a third HREELS peak appears at 50 meV as H (D) coverage approaches saturation. This peak does not shift in energy with isotopic substitution, yet cannot be explained by contamination. The intrinsic width of the loss peaks depends on the Re concentration in the surface region and becomes broader with increasing x. This broadening can be attributed to surface inhomogeneity, but may also reflect increased delocalization of the adsorbed hydrogen atom. 相似文献
114.
Antonio F. Fuentes M. Garza-Garc?&#x;a G. Mendoza-Suárez U. Amador 《Journal of solid state chemistry》2003,175(2):299-305
We describe in this work the synthesis and crystal structure of five rare earth and Mo(VI) or W(VI) containing complex perovskites. The compounds studied are Ba(Dy2/3Mo1/3)O3, Ba(Dy2/3W1/3)O3, Ba(Gd2/3Mo1/3)O3, Ba(Gd2/3W1/3)O3 and Ba(Sm2/3W1/3)O3 and were prepared starting from solutions, by the polymeric precursors method. Structural characterization by HREM, SAED and powder XRD revealed the five compounds to be ordered cubic perovskites, SG Fm-3m (225), with a cell parameter double of that of a simple perovskite cell and increasing as the size of the trivalent lanthanide ion increases (Dy<Gd<Sm). 相似文献
115.
Thin films of molybdenum trioxide were deposited on glass substrates employing direct current (DC) magnetron sputtering by
sputtering of molybdenum at different oxygen partial pressures in the range 8 × 10−5–1 × 10−3 mbar and at a substrate temperature of 473 K. The glow discharge characteristics of magnetron cathode target of molybdenum
were studied. The influence of oxygen partial pressure on the structural and optical properties of molybdenum trioxide films
was investigated. The films formed at an optimum oxygen partial pressure of 2 × 10−4 mbar were polycrystalline in nature with orthorhombic α- phase and an optical band gap of 3.16 eV. The refractive index of
the films formed at an oxygen partial pressure of 2 × 10−4 mbar decreased from 2.08 to 1.89 with increase of wavelength from 450 to 1,000 nm, respectively.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006. 相似文献
116.
K.L. Man 《Surface science》2007,601(16):L95
The formation and stability of Cu, Ag and Au-induced c(2 × 2) alloys at the Mo(1 0 0) and W(1 0 0) surfaces have been investigated with low-energy electron microscopy and diffraction. The ordered alloys transform to disordered overlayer structures at elevated temperature. Comparison of the transformation temperatures with energetics obtained from first principles calculations reveals the vibrational entropic contribution to the system free energy that defines alloy thermal stability. Effective Debye temperatures for metal adatoms are determined that exhibit the expected mass and bond strength dependence. 相似文献
117.
Synthesis and characterization of molybdenum complex with tolbutamide (an oral antidiabetic drug) have been studied. The conductometric titration using monovariation method indicates that complex is non-ionic and of L2M type. Analytical data agree with the molecular formula (C12H17N2O3S)2Mo·2H2O. Structure of the complex was assigned as octahedral in which ligand molecules lie horizontally joining the central molybdenum atom and one water molecule, each attached vertically with the metal. Infra-red spectral studies confirm the coordination of sulphonyl oxygen on one side and enolic oxygen attached from other side with the metal ion. IR and 1H NMR studies support structure II proposed on the basis of analytical data. Magnetic susceptibility data suggested that the complex is diamagnetic. Thermal studies support the presence of ligand moieties and coordinated water. X-ray diffraction data also support the complex formation. 相似文献
118.
The combined derivative spectrophotometry developed in this paper is a new method, which can be used to determine multicomporent mixture simultaneously and may improve the sensitivity and accuracy of the measurement remarkably. Two practical tests were carried out to verify the correctness of the theory, and the results are satisfactory. 相似文献
119.
Numerous analogies between organic and inorganic chemistry have emerged in recent years. The most prominent example is the isolobal relationship. Many reactions have shown that metal-metal double and triple bonds exhibit a pattern of reactivity similar to that of alkenes and alkynes. In compounds containing a σ2π4 triple bond between molybdenum and tungsten atoms, the M? M bond order can be increased from three to four by reductive elimination or decreased from three to two or one by oxidative addition. Complexes with M?M bonds can be used to prepare clusters or can serve as catalysts. In this review relationships between structure (electronic and stereochemical) and reactivity that are characteristic for modern inorganic chemistry are discussed. 相似文献
120.
Two new molybdenum (VI) monophosphates CsMoO2PO4 and TlMoO2PO4 have been synthesized by solid state chemistry. Their structure were determined from single crystal X-ray diffraction studies. The frameworks MoO2PO4 delimit tunnels in which are located the univalent cations. Structural relationships between the different monophosphates of the AMoO2PO4 series with A = Ag, Na, K, Tl, Cs, are presented in which two kinds of frameworks appear owing to the size of the univalent cations. 相似文献