Materials Literature
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High‐temperature electrical conductivity, Seebeck coefficient, and thermal conductivity measurements were used to study the effects of different cation substituents on electrical and thermal transport in YCrO 3 and LaCrO 3 . The substitution of divalent Ca and Sr for Y and La, respectively, resulted in the formation o…
Abstract Well-crystallized perovskite-type oxides could be synthesized at temperatures as low as 550–650 °C by the calcination of amorphous citrate complex precursors. The large specific surface areas of the oxides obtained suggest that the citrate process is very promising for preparing perovskite-type oxide catalyst…
Abstract The continuous conversion of smectite to illite in samples from the Shinzan hydrothermal alteration area of Japan has been examined by X-ray powder diffraction (XRD) and transmission (TEM) and analytical transmission electron microscopy (AEM). TEM shows that randomly interstratified illite/ smectite (I/S) con…
The Morin temperature (${T}_{M}^{0}$) of annealed, monodispersed, nearly spherical particles having diameters (d) between (0.07--0.62) \ensuremath{\mu}m have been investigated. A plot of ${T}_{M}^{0}$ versus 1/d is linear. The extrapolation of this plot between 230 and 262 K to d=\ensuremath{\infty} gives ${T}_{M}^{0}…
A new ATP-dependent, casein-degrading proteolytic complex has been identified and partially purified from Escherichia coli. The proteolytic complex can be isolated from wild-type cells as well as from mutants in which the gene for the ATP-dependent Lon protease is deleted. The complex consists of at least two componen…
We consider ferroelectric compounds created by relative ionic displacements between two or more sublattices (``displacive'' phase transitions). For these ferroelectric materials the nonbonding p orbitals of oxygen ${(0}^{2\mathrm{\ensuremath{-}}}$) or chalcogen (${\mathrm{S}}^{2\mathrm{\ensuremath{-}}}$, etc.) ions pl…
The complex dielectric constant has been measured in a room-temperature ferroelectric liquid-crystal mixture. We have resolved the experimental data into the Goldstone mode and the soft mode and for each mode determined the dielectric strength and the corresponding relaxation frequency. The results are compared with t…
Anomalously large current plateaus observed in the cyclic voltammograms of some conducting polymers such as polypyrrole have been recently interpreted as the charging of a large capacitance taking place in the polymer in the oxidized state. The nature and the origin of such capacitance is actually discussed either in…
A fracture mechanics model is developed for nontransforming ceramics that show an increasing toughness with crack extension ( R ‐curve, or T ‐curve, behavior). The model derives from the observations in Part I, treating the increased crack resistance as the cumulative effect of grain bridging restraints operating behi…
Direct microscopic evidence is presented in support of an explanation of R ‐curve behavior in monophase ceramics by grain‐localized bridging across the newly formed crack interface. In situ observations are made of crack growth in tapered cantilever beam and indented flexure specimens of a coarsegrained alumina. The f…
In capacitors with metallized organic dielectrics electrical breakdown may be of great importance for reliability. In the case of pinholes in the dielectric, the thin electrodes in the surroundings are vaporized within a few μs and therefore the pinholes are insulated. This process is closely associated with gas react…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and characterization of five-coordinate high-spin iron(II) porphyrin complexes with unusually large quadrupole splittings. Models for the P460 center of hydroxylamine oxidoreductase from NitrosomonasH. Nasri, J. Fischer, R. Weiss, E. Bill, and A. TrautweinCite this…
Abstract Thermogalvanic cells containing a redox couple of [Fe(CN)6]4−⁄3− or Fe2+⁄3+ as an electroactive species were built for thermoelectric conversion from low-grade heat with a temperature less than 100 °C. The distance between high- and low-temperature electrodes was set to 1 mm in order to produce a high power d…
The mechanism of load transfer along unreinforced concrete interfaces by means of friction has been experimentally investigated for several surface roughnesses. The results of the parametric studies investigating the frictional behavior of interfaces under both monotonic and fully reversed large displacements are pres…
A one-dimensional transient thermal model has been developed to predict the thermal response of a decomposing, expanding polymer composite exposed to high temperatures. Both the decomposition and thermochemical expansion, as well as the storage of decom position gases in the solid material were considered in the formu…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSensitization of titanium dioxide in the visible light region using zinc porphyrinsK. Kalyanasundaram, N. Vlachopoulos, V. Krishnan, A. Monnier, and M. GraetzelCite this: J. Phys. Chem. 1987, 91, 9, 2342–2347Publication Date (Print):April 1, 1987Publication History Published…
Abstract Experiments were performed to validate the model for the nucleation of microcellular foams in amorphous thermoplastic polymers. The polystyrene‐zinc stearate system was chosen as the model system. Other additives such as stearic acid and carbon black were also investigated. Molecular weight and orientation ef…
Experimental data on phase relations in the CaCO3-MgCO3-FeCO3 ternary by Goldsmith et al. (1962) are inconsistent with those of Rosenberg (1967). These inconsistencies cannot be reconciled by the pressure or temperature differences between the two sets of experiments. Available reversed experiments on the binary syste…
Abstract Microcellular polymer foams exhibit greatly improved mechanical properties as compared to standard foams due to the formers' small bubble size. Microcellular foams have bubbles with diameters on the order of 10 microns, volume reductions of 30 to 40 percent, and six or seven times the impact strength of solid…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical polymerization of amino-, pyrrole-, and hydroxy-substituted tetraphenylporphyrinsA. Bettelheim, B. A. White, S. A. Raybuck, and Royce W. MurrayCite this: Inorg. Chem. 1987, 26, 7, 1009–1017Publication Date (Print):April 1, 1987Publication History Published on…