Synthese und Kristallstruktur von Vanadium(III)‐borophosphat,V2[B(PO4)3]

Synthesis and Crystal Structure of Vanadium(III) Borophosphate, V₂[B(PO₄)₃] By reaction of boron phosphate, BPO₄, and vanadium(IV)‐oxide, VO₂, at 1050 °C a hitherto unknown vanadium(III)‐borophosphate is formed. Its composition was found to be V₂BP₃O₁₂, its structure was elucidated by single crystal X‐ray diffraction, the cell parameters are: a = b = 13.9882Å; c = 7.4515Å; α = β = 90°, γ = 120°; Z = 6; space group: P6 3/m. Noteworthy features of the structure are V₂O₉ units (two V^IIIO₆ octahedra connected via their faces) and isolated trisphosphatoborate groups, B(PO₄)₃. By shared oxide ions, the aforementioned groups are interconnected, thus forming a three dimensional network. The structural relation between the title compound and an analogous chromium compound is discussed.     

Oxidation of glucose at electrodeposited platinum electrodes

The oxidation of glucose at low concentrations was studied at electrodeposited platinum electrodes in 0.1 M HClO₄ using an electrochemical quartz crystal microbalance (EQCM). Experiments were performed over the whole potential range and then over selected regions of potential to investigate the processes giving rise to specific features in the cyclic voltammetry and mass response. In the region of potential where adsorbed hydrogen is present, EQCM experiments reveal the presence of adsorbate derived from glucose through the removal of features associated with the presence of adsorbed anions in the background electrolyte. Cycling over this potential region leads to a decrease in the mass of the electrode as the coverage of poisoning species increases. In the double-layer region of potential an increase in mass is seen as the adsorbate is oxidized and removed from the electrode surface, and is suggested to be a result of the replacement of adsorbed residues (formed from progressive oxidation of glucose) by both anions and fresh reactant. Restriction of the electrode potential to values above 0.2 V (SCE) prevents poison formation and mass responses indicate the presence of adsorbed glucose between 0.2 V and 0.6 V. Mass responses accompanying voltammetry and injection experiments also indicate that glucose or species derived from it can adsorb on an oxidized platinum surface.     

1.1 Fundamentals, methods, apparatus, reagents, automation, data processing

Abstracts1 General analytical chemistry

1.1 Fundamentals, methods, apparatus, reagents, automation, data processing     

Nuclear Dynamics and Electronic Effects of Hydrogen on Solid Surfaces

Hydrogen is involved in a variety of chemical processes on surfaces. While hydrogen exhibits vibrational and rotational dynamics in its adsorption state, it in some cases undergoes diffusion into the substrate as well as on the surface, and participates in chemical reactions. Furthermore, hydrogen exchanges an electron with surfaces having a significant effect on the surface electronic structure. In this personal account, we review our recent studies on surface nuclear dynamics of hydrogen, hydrogen transport across surfaces, catalytic hydrogenation/isotope exchange reactions, and charge transfer between the surface and hydrogen by using a depth‐resolved technique of nuclear reaction analysis and a quantum‐state‐selective detection of resonance enhanced multiphoton ionization in combination with surface science techniques. As a future prospect, we refer to ultraslow μ spin rotation spectroscopy for a direct probe of the hydrogen charge state at surfaces.     

Strength Analyses of Laminated Composite Structures Based on Different Theories

Modern materials, such as composite ones, slowly replace conventional materials in structures of different kind and their growing popularity is caused by their multiple advantages. Through selection of parameters, such as number of layers, thickness of layers, direction of arranging fibers, or material from which internal and outside layers are made, it is possible to control properties of a structure. In the result, structures made of composite materials have high ratio of flexural stiffness to weight. The goal of this paper is to compare three theories of laminated composite plates and shells with the help of the multilayered rectangular plate model subjected to crosswise pressure perpendicular to the surface of a plate. Comparison was made for the classical laminated theory (CLT), first-order laminated theory and third-order laminated theory (TSDT). In all these theories, the number of parameters describing the displacement doesn't depend on the number of layers. For each of these theories strains and displacements were determined. Additionally, the computations time for every method were compared. Obtained results are presented in the form of tables. The analysis of the obtained solutions will be used as the base in choosing the best theory in multicriteria optimization process of composite thin-walled structures. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Growth and Characterisation of Silicon Crystallites on Laser Structured Glass

Selective growth of silicon crystallites on glass, seeded from silicon saturated metallic solution droplets is demonstrated. These droplets are deposited in micropore arrays which are generated in the glass substrate by ultrashort laser pulses. In this way, an equidistant distribution of crystallites can be achieved by preferred nucleation in the micropores. Additionally, a crystallite selection occurs corresponding to the tip geometry. The material transport is governed by the vapour-liquid-solid (VLS) mechanism. The morphological characterization of micropores and grown crystallites is performed by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Focused Ion Beam (FIB) method.     

Raman spectrum of Sr0.61Ba0.39Nb2O6

The Raman spectra of a single crystal of strontium barium niobate were recorded in the temperature range–193 to 140°C. The configurations studied were X(ZZ)Y, X(YZ)Y, X(YX)Y, Z(XX)Y, Z(YZ)Y and Z(XZ)Y. The behavior of integrated reduced intensities, band widths and band centers with temperature indicated that the ferro-electric transition temperature was near 65°C. The Raman data were not consistent with a classical Landau transition. Disorder-induced first-order spectra were observed and attributed to the disordered nature of the crystal Evidence was found for a possible phase transition near 120°C.