Materials Literature
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We have studied the temperature dependence of dielectric relaxation times in terms of the peak frequency fmax(T) of dielectric loss ε″(ω) and the dc-conductivity σdc(T) of several glass-forming liquids, covering 12 decades in the peak frequency fmax and 9 decades in σdc. Although dc-conductivity samples the mobility o…
Direct electrodeposition of zinc oxide films is reported for the first time. That this method of preparation is suited to large‐scale production could be important for applications of ZnO, e.g., in solar cells. In addition to a description of the preparation and properties of the films, it is shown that the morphology…
Results of a detailed investigation of the structure and electron-transport properties of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{A}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ (A=Ca, Sr) over a wide range of compositions are presented along with those of parent ${\mathrm{LaMnO}}_{3}$ containing different…
A suitable relationship between the linear refractive index n0, the energy gap Eg, and the nonlinear refractive index n2 has been looked for on the basis of experimental and theoretical data reported in the literature for numerous simple oxides. It has been established that the nonlinear refractive index increases wit…
A mixed oxide (Zn1−xAlx)O exhibits promising thermoelectric properties attaining a dimensionless figure of merit ZT of 0.30 at 1000 °C, which value is much superior to other oxides and quite comparable to conventional state-of-the-art thermoelectric materials. The addition of a small amount of Al2O3 to ZnO results in…
The average electronic oxide polarizability α02− of numerous single component oxides has been calculated on the basis of two different properties: linear refractive index n0 and energy gap Eg, which have demonstrated remarkable correlation. The optical basicity Λ of the oxides has been estimated on the basis of averag…
We report high resolution electron microscope (HREM) observations and atomistic simulations of the bending of single and multi-walled carbon nanotubes under mechanical duress. Single and multiple kinks are observed at high bending angles. Their occurrence is quantitatively explained by the simulations, which use a rea…
Mechanical and processing properties of recycled polyvinylchloride (PVC, from bottles and pipes) were compared with those of virgin pipe grade PVC. Blends of recycled and pipe grade PVC were also prepared and characterized. It was found that the particle size and the restabilization of the recycled PVC are the two mai…
The simulation results based on the devulcanization model presented in Part I of this study are described for devulcanization of SBR vulcanizates. The vulcanizates are conveyed by a single-screw extruder to a thin gap between a stationary die and a vibrating horn. Gapwise velocity, temperature, and shear-rate distribu…
Tire and rubber waste recycling is an important issue facing the rubber industry. In addressing this issue, the present article describes the first attempt to formulate a model and to simulate a novel continuous ultrasonic devulcanization process. The proposed model is based upon a mechanism of rubber network breakup…
The present work is intended to investigate the thermopower and electrical conductivity studies of some substituted strontium W-type hexagonal ferrites as a function of composition and temperature. On the basis of the sign of the Seebeck coefficient (S), the ferrites under investigation have been classified as n-type…
We report measurements of the temperature and pressure dependence of ultrasonic modulus and specific volume in polystyrene between 50 and 280°C and applied pressures up to 775 bar. The volumetric glass transition temperature is found to vary linearly with pressure. Furthermore, it coincides with the temperature at whi…
Several intramolecular charge transfer fluorescence probes, such as the dansyl amides (1a-d), 4-dimethylamino-4′-nitrobiphenyl (2) and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (3), have been developed and evaluated. The fluorescence emission of the probes is sensitive to both the solvent polari…
The melting behavior of poly(butylene terephthalate) and its blends with bisphenol-A polycarbonate was investigated with differential scanning calorimetry. The aim of this work was to determine the equilibrium melting temperature and its dependence on the blend composition using the Hoffman-Weeks plots. It is shown th…
The miscibility of polyetherimides (PEIs) with epoxy monomers based on diglycidylether of bisphenol-A (DGEBA), and with reactive mixtures based on stoichiometric amounts of DGEBA and an aromatic diamine (DA) {either 4,4′-diaminodiphenylsulfone (DDS) or 4,4′-methylenebis[3-chloro 2,6-diethylaniline] (MCDEA)}; was exper…
Properties of the proton transfer in (KDP) are examined on the basis of a model that was proposed to explain the mechanism of the phase transition from a ferroelectric phase to a paraelectric phase; it is found that, in the paraelectric phase, a proton transfers from one site to the other site at a jump rate of the or…
The electrical conduction of free-standing porous silicon layers, obtained from n+ silicon with various anodization currents and illumination conditions, has been investigated in vacuum as a function of the temperature in the interval 300-210 K. The two-contact I-V characteristic is determined by the metal/porous sili…
From Methanopyrus kandleri, the most thermophilic methanogen known so far, we have purified to homogeneity a protein complex of high molecular mass. Image analysis of transmission electron micrographs revealed a barrel-shaped particle composed of two rings with 8-fold symmetry. Only one type of subunit could be detect…
Crystalline carbon nitride films have been synthesized in a rf plasma assisted hot filament chemical vapor deposition system. Large crystalline grains up to ∼10 μm in size as well as film-like regions are observed in the morphology of the films. β-C3N4 with two groups of lattice parameters (one is consistent with the…
Ferroelectric layered-oxides SrBi2Ta2O9 thin films were prepared on Pt coated Si wafers and single-crystal sapphire by metalorganic chemical vapor deposition (MOCVD). The films were specular and crack-free and showed complete crystallization at temperatures between 650 and 700 °C. Good ferroelectric properties were ob…