Materials Literature
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Wir haben die Systeme CuGa5S8/CuIn5S8 und AgGa5S8/AgIn5S8 an abgeschreckten Präparaten mit Röntgenpulver- und Einkristallmethoden untersucht. Im System AgGaxIn5–xS8 wird bis x < 2 eine Phase mit Spinellstruktur gebildet. Für 2 < x ≤ 3 existiert eine Phase, die in einer hexagonalen Schichtstruktur kristallisiert. Die S…
The mechanical properties of a ternary system consisting of low density polyethylene (LDPE), poly(ethylene-co-methacrylic acid) copolymer (EMAA) and wood flour (WF) were investigated. For a better understanding of the mutual interactions between the components, binary blends LDPE/EMAA and EMAA/WF were studied as well,…
Syndiotactic polystyrene (sPS) of a low molecular weight (M̄w = 63 000 g/mol) was found to develop only a β-type unit cell upon melt crystallization at all temperatures. Correlation between the lamellar morphology and melting behavior in the sPS has been demonstrated in this study. When crystallized at lower temperatu…
The effect of excess lead oxide on the microstructure and ferroelectric properties of lead zirconate titanate (PZT) films was studied in PZT-based thin-film capacitor structures. It is shown that excess lead in the form of lead oxide is localized at the grain boundaries and film-platinum electrode interfaces, which ca…
Several series of aromatic polyethers and polybenzoxazoles with high thermal stability and low dielectric constant were prepared and characterized. The polyethers were synthesized by nucleophilic aromatic displacement of fluorine with phenoxides. In order to avoid strongly polar groups such as carbonyl and sulfone, tr…
The electric transport properties of single-crystal and ceramic samples of Pr1−xSrxMnO3 perovskites were investigated and correlated with structural and magnetic data. Analysis of the experimental data leads to the following conclusions: (i) the phase boundary between the ferromagnetic and A-type antiferromagnetic gro…
High quality magnetoresistive La(1−x)CaxMnO3 thin films have been prepared by the chemical solution deposition technique. A solution of propionate precursors of lanthanum, calcium, and manganese in propionic acid was used for this purpose. Films of varying compositions (x varying from 0.1 to 0.4) were spin coated on t…
To study the pitting characteristics of two nickel-based alloys in aggressive acidic environments, potentiodynamic anodic polarization of Alloy 600 (UNS N06600) and Alloy 601 (UNS N06601) was carried out in the presence of various concentrations of sodium chloride (NaCl) in 0.1 M sulfuric acid (H2SO4) at 30°C, 60°C, a…
Binary accelerator systems are widely used in vulcanisation of rubbers, providing more effective vulcanisation than using single accelerator systems. It has been reported previously that when thiourea is used in binary systems, it favours the cleavage of S–S, S–C, or S–N bonds in primary accelerators such as tetrameth…
The naturally layered colossal magnetoresistive manganites La2−2xSr1+2xMn2O7 exhibit an extremely varied range of magnetic and electronic behavior over a very narrow composition range between x=0.3 and x=0.5. The successful synthesis in our laboratories of compounds with nominally greater than 50%Mn4+ concentration ha…
The NRL developed tight-binding method has been very successful in describing the properties of nonmagnetic elemental metals and semiconductors with accuracy comparable to first-principles methods. In this article we discuss extensions of the method to magnetic systems. We first show that the method correctly predicts…
In this work, a molecular model is proposed to account for the stress-strain relationships of spherulitic polymers. To describe the yielding behavior of spherulitic polymers, we introduced a new structural unit, i.e. the lamellar cluster, which is represented by several stacked lamellae bound by some tie molecules. It…
Coupling the Knudsen effusion method with mass spectrometry has proven to be one of the most useful experimental techniques for studying the equilibrium between condensed phases and complex vapors. The Knudsen effusion method involves placing a condensed sample in a Knudsen cell, a small enclosure, that is uniformly h…
A model previously developed by Petch enables an estimate of the impact transition temperature (ITT) of low carbon structural steels to be made from measurements of grain size and carbide thickness. In the present work, various laboratory heat treated and commercially processed structural steels were assessed in order…
The effects of inclusions on corrosion resistance of high-Cr-containing ferritic steels were studied using electrochemical tests (anodic polarization and electrochemical noise [EN]) and a ferric chloride (FeCl3) test in chloride solution. For this purpose, the inclusion type and size in the matrix was controlled by th…
La microscopie par contraste d'interference differentielle (DIC) permet d'obtenir des images des microfibrilles de cellulose dans la couche S2 des fibres de membrane secondaire delignifiees. L'utilite de cette methode microscopique simple de mesure de l'angle des microfibrilles (MFA) a ete validee par rapport a la dif…
Gel points, predicted using Ahmed-Rolfes-Stepto (ARS) theory and a Monte-Carlo (MC) simulation method accounting for intramolecular reaction, are compared with experimental data for polyester (PES)-, polyurethane (PU)- and poly(dimethyhl siloxane) (PDMS)-forming polymerisations. The PES and PU polymerisations were fro…
The pH dependence of the sonochemi-luminescence (SCL) of luminol at 141 kHz was investigated and compared to the effect of pH on its fluorescence emission intensity. From the fluorescence intensity, the pK a1 * and the pK a2 * values were determined to be 6.4 and 10.5 respectively, which was consistent with changes ob…
Abstract A unique way to dramatically enhance the brightness of single layer and stacked reflective cholesteric LCDs is shown. The LC aligning surfaces are treated to provide varying degrees of homogeneity while maintaining the bistability. The result is reflective displays with exceptionally high brightness approachi…
FERROELECTRIC LIQUID CRYSTALS -FLCs. A SYNTHETIC APPROACH. Synthetic methods used for the synthesis of the Ferroelectric Liquid Crystals (FLCs) will be considered with emphasis on the chiral synthesis methodologies and mesomorphic electrooptical properties.