Materials Literature
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A new phase in the Si‐Al‐O‐N system has been identified, following syntheses based on the nitridation of silicon/clay mixtures at low temperatures (<1350°C). The structure of the new phase was determined using a combination of diffraction and high‐resolution imaging techniques, and this new phase possessed the same…
The present paper reviews the results oblained by the authors in the last three years. By applying in-situ (pamp and probe) EXAFS to reversible photostructural changes in chalcogenide vitreous semiconductors we have found an increase in the average coordination number of selenium species in the photoexcited state whic…
The effect of structural changes on dc ionic conductivity — from room temperature to the melting point at atmospheric pressure — of rubidium nitrate single crystals grown by the slow evaporation method is presented. The anomalous variation of conductivity at structural phase transition points is interpreted on the bas…
We have electropolymerized 1,1′‐bis[[ p ‐phenylamino(phenyl)]amido‐]ferrocene from CH 3 CN , tetrahydrofuran (THF), and CH 2 Cl 2 to form an alternating main chain polymer of diphenylbenzidine and ferrocene. As a comparison, we have electropolymerized 1,4 bis[[ p ‐phenylamino(phenyl)]amido‐]benzene which lacks the ele…
Abstract The crystal structure of szenicsite, Cu 3 MoO 4 (OH) 4 , orthorhombic, a = 8.5201(8), b = 12.545(1), c = 6.0794(6) Å, V = 649.8(2) Å 3 , space group Pnnm , Z = 4, has been solved by direct methods and refined by least-squares techniques to an agreement index ( R ) of 3.34% and a goodness-of-fit ( S ) of 1.11…
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A promising way to reduce N2O emissions is the catalytic decomposition into the elements using transition metal-exchanged zeolites. Cu-ZSM-5 is an especially active catalyst for this reaction. This paper reports on the influence of the copper content and the Si/Al ratio of the parent zeolite on the catalytic activity…
The quadratic electrooptic coefficients g 1111 and g 2211 have been measured interferometrically in ADP at room temperature. In addition, ‖g 1111-g 2211‖ was determined by a dynamic polarimetric technique at the same temperature. Both experiments yield values for g 1111-g 2211 at 21 C and λ = 0.633 μm with an average…
An actinometric optical emission spectroscopy (AOES) study of the trends in the concentrations of the plasma species H, CH, CO, OH, and CN in film-producing glow discharges of mixtures of isopropanol and nitrogen was undertaken. Conventional AOES was used to obtain the trends in the plasma concentrations of these spec…
double‐oxide films were formed on Pt substrates by low‐pressure metallorganic chemical vapor deposition using iron acetylacetonate and tetraisopropoxytitanium as precursors and as a reaction gas. Fe‐Ti alloys were fabricated by an ion‐beam sputter and an arc‐melting process. The corrosion resistances of the films and…
Tetramethylammonium sulfate, [N(CH 3 ) 4 ] 2 SO 4 , was prepared in high purity via ion exchange. Two reversible first-order phase transitions at 263 ± 3 and 462 ± 3 K have been established by differential thermal analysis and temperature-dependent X-ray powder diffraction. Crystal structure determinations at 223 and…
Several worst case scenarios were carried out for safety evaluation of an existing nitration process. Heterogeneous nitric acid decomposition is observed to be the worst credible scenario in the toluene nitration process. Fire or explosion may subsequently develop due to temperature or pressure runaway from the undesi…
Incommensurate tridymite L3-T O (MX-1) shows a cascade of five phase transitions at 65, HO, 150, 200, and 380 ℃ upon heating. The X-ray diffraction patterns were investigated with a Buerger precession camera revealing a sequence of four incommensurate phases in the range from room temperature to 200 ℃. The phases form…
Film-forming properties of plant proteins vary, depending on the protein's amino acid composition and molecular characteristics. Proteins from soy bean, wheat, and corn are readily available and films from these proteins have been investigated extensively. The proteins are normally dissolved or dispersed in suitable s…
A number of the new chiral side-chain menthyl containing copolymers were synthesized. Phase behavior, optical properties, and structures of the synthesized copolymers with different compositions were studied. For the first time a specific mesophase induction in side-chain copolymers, containing nonmesomorphous side gr…
Despite angle dependence and polarization selectivity, the color of cholesteric liquid-crystal (CLC) polysiloxane films can be quantified by standard colorimetry. A new fractured form of the film called “flakes” makes it possible to use the Center of Gravity Color Mixing Principle to predict the chromaticity of CLC co…
Bis(benzene)chromium [(η 6 -C 6 H 6 ) 2 Cr] (BBC) is shown to readily trap radical species R (R = H, D, isobutyronitrile (IBN)) to form complex paramagnetic adducts whose structure has been identified in frozen solution by ENDOR (electron nuclear double resonance spectroscopy). It is shown that radical attack yields t…
Results from a high-speed photographic study made at a framing speed of one million frames per second of the disintegration of Prince Rupert's drops made of soda-lime glass and immersed in a transparent liquid of a matching refractive index are described. The refractive index matching made the cracks through the drop…
A strong dependence of the rotational dynamics of the mesogenic units (β-relaxation) on the order of the mesophase was found in sidechain liquid crystal polymers. The preexponential frequency factor, \documentclass{article}\pagestyle{empty}\begin{document}$ f_{\beta \infty }^* $\end{document} and the activation energy…
Iron bands, fragipans and duripans are common in yellow low-activity clay soils developed from the Barreiras Group in coastal plateaus of northeastern Brazil. Such indurated horizons are found in depressions of the plateaus where sugar cane growth is greatly reduced. Little research has being done on the nature of the…