Materials Literature
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Alkali and barium hydroxide promotion of the Cu/ZnO methanol synthesis catalysts has been investigated with the following results: (i) at low temperatures, high H 2 /CO ratios, water-free and CO 2 -free synthesis gas, the alkali promote methanol synthesis rates in the order Cs>Rb>K>Na>Li; (ii) the alkali hydroxides ar…
Abstract 11,11,12,12‐Tetracyan‐9,10‐anthrachinodimethan [ 3a , X = C(CN) 2 ] besitzt im Kristall eine stark von der Planarität der Stammverbindung Anthrachinon abweichende Geometrie. Der Winkel zwischen den beiden Benzoanellanden beträgt 145°; die Dicyanmethylen‐Einheiten sind entgegengesetzt gefaltet und schließen ei…
A microdynamic theory for the self-diffusion coefficient, which involves a wave-number-dependent viscosity, eta (q), is successfully tested on a hard-sphere system. The models the authors introduce for eta (q) are adapted to the Lennard-Jones fluid. New molecular dynamics data for the relative diffusion coefficient, i…
Stage purity and staging transitions of potassium-graphite intercalation compounds have been investigated in situ by high-resolution x-ray scattering. The positions and profiles of ($00L$) Bragg reflections indicate staging disorder in thermal equilibrium for all compounds larger than stage 2, which increases with inc…
We report electron-microscopy and high-resolution x-ray-scattering measurements of rapidly quenched ${\mathrm{Al}}_{6}$Mn. The electron-diffraction pattern shows icosahedral symmetry. Peaks in the x-ray-diffraction pattern can be indexed to a mixture of fcc Al and a phase whose reciprocal lattice is described by a sum…
A description is given of basic regularities in the formation of domains and twins during phase transformation involving movement of a single plane phase boundary.
The Burgers vectors of secondary grain boundary dislocations, forming networks in near ~9, ~27a, ~27b and ~81a grain boundaries in polycrystalline specimens of a Cu +6 at. % Si alloy, have been determined using the technique of image matching, which involves a comparison of experimental and theoretical electron microg…
Surfactant is painted partially on a cylindrical insulator having a "back-side" (Inner) electrode, to change the distribution of the accumulating surface charge (residual charge) generated by ac partial discharge. The surfactants used are Neogen T®, Catiogen L®, or Tween 20®; the insulating material is polyvinyl-chlor…
Abstract Die neue Verbindung Na 6 Si 2 Se 8 kristallisiert monoklin in der Raumgruppe P2 1 /c (Nr. 14) mit den Gitterkonstanten a = 727,1(3) pm, b = 1700,7(5) pm, c = 1378,3(4) pm, β = 99,44(8)°. In der Struktur sind zwei SiSe 4 ‐Tetraeder über eine Se–Se‐Bindung zu diskreten [Si 2 Se 8 ] 6− ‐Anionen verknüpft.
Abstract Both boron nitride and boron carbide were synthesized by the pyrolysis of the boric acid/1,2,3-propanetriol condensation product above 1300 °C in N2, whereas the thermal treatment in an Ar flow yielded boron carbide.
Synopsis Image analysis provides a practical method for studying the cutaneous relief and better understanding of the formation of wrinkles during ageing and their regression induced by an anti-wrinkle product. Quantimet 900 degrees allows a fully automated analysis of 40 replicas of skin surface per cycle of 6 h. The…
An atomistic model has been used to calculate the dipole tensor of vacancies and impurity-vacancy (IV) pairs in ionic crystals. The program PDINT, developed for f.c.c. ionic crystals and based on a generalized Mott-Littleton procedure, was used. Two methods of evaluating dipole tensors of defects were investigated, th…
Abstract With the purpose to correlate the thermal stability of PVC with its structural defects, a number of studies have been carried out on 13 PVC samples and in some cases on their fractions. These studies are dealt with structural determination on the one hand and thermal degradation tests on the other hand.
The system with two order parameters is investigated theoretically. This system is described by Landau model with a biquadratic coupling between the two order parameters, each of which involves the second order phase transition. Phases which can result from competition between the order parameters are found, and phase…
Abstract In recent years only a few totally new plastics have been developed, since suppliers are finding it quicker and less expensive to tailor existing resins to meet the requirements of a specific application by alloying. The properties of an alloy of polycarbonate and a proprietary copolyester have been fully cha…
The results of neutron diffraction (ND) and inelastic incoherent neutron scattering (IINS) studies on phase transitions and vibrational spectra in superionic conductor CsHSO4 at pulsed reactor IBR-2 are reported. It is shown that in the temperature range 123–420 K there are three phases (III, II, I) in CsHSO4 crystal…
Abstract Certain mixtures of TFE/CHCl 3 were found to be excellent solvents for aliphatic polyamides such as nylon‐6, nylon‐66, nylon‐11, nylon‐12, nylon‐69, nylon‐610, and nylon‐612. Intrinsic viscosities were measured and Mark–Houwink coefficients determined for nylon‐6/TFE/CHCl 3 , indicating TFE‐rich mixtures to b…
Results are presented which show that for environment-sensitive cracking the changes in environment composition or potential that may occur in pits, crevices, or cracks are probably as important as the stress concentration associated with such discontinuities. However, with some solutions, especially those in which th…
Computer simulation techniques based on generalized Mott-Littleton methods have been used to investigate defect structures in systems resulting from the incorporation of Mn2 +, Cd2+ and Pb2+ ions into NaCl, KC1 and KBr crystals. Two-body interionic potentials based on the simple shell model were used in the calculatio…
Abstract Recent developments in the phenomenon of growth rate dispersion are surveyed with a particular emphasis on its characterisation. Most of the characterisation work concerning growth rate dispersion has been carried out under negligible nucleation conditions in batch configurations. Analytical solutions to the…