Materials Literature
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The electrochemical properties of solutions of niobium chlorides in the fused eutectic were studied by transient electrochemical techniques. The fundamental role of temperature was determined. At temperatures ranging from 380–600°C, two reversible redox reactions were detected : , and . Reduction of Nb(III) led to met…
The tribological behavior of a SiC–TiB 2 ceramic‐matrix composite was evaluated using a pin‐on‐flat contact configuration in reciprocating sliding. A steady‐state friction coefficient of about 0.55 and an average specific wear rate of about 2 × 10 ‐6 mm 3 ·N ‐1 ·m ‐1 were measured. The mechanisms of material removal i…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMiscibility and cocrystallization in homopolymer-segmented block copolymer blendsK. P. Gallagher, X. Zhang, J. P. Runt, G. Huynh-Ba, and J. S. LinCite this: Macromolecules 1993, 26, 4, 588–596Publication Date (Print):February 1, 1993Publication History Published online1 May…
The width of the argon 2s level was experimentally obtained from x-ray emission-spectroscopy (2.25\ifmmode\pm\else\textpm\fi{}0.15 eV) and x-ray photoelectron-spectroscopy (XPS) (2.25\ifmmode\pm\else\textpm\fi{}0.05 eV) measurements. A theoretical value of 1.85 eV was obtained by a Green's-function calculation. A high…
Abstract In groups of isotypic ionic crystals the product of the mean value of the principal elastic constants and of the molecular volume, the S -value, is an almost constant quantity. Even chemically related ionic compounds possess similar S -values. The different “hardness” of the ions and the number of contacts of…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicelles series. 31. Building blocks for cascade polymers. 11. Synthesis of functionalized cascade cores: tetrakis(.omega.-bromoalkyl)methanesGeorge R. Newkome, Sadao Arai, Frank R. Fronczek, Charles N. Moorefield, Xiaofeng Lin, and Claus D. WeisCite this: J. Org. Chem. 1993…
Abstract Illite from the Potsdam Sandstone (lower Ordovician) of Northwestern New York was studied by powder X-ray diffraction, scanning electron microscopy, and chemically analyzed and dated by the K/Ar method. The texture and ages of 360 and 392 Ma on two samples establish that the mineral is authigenic and relative…
ADVERTISEMENT RETURN TO ISSUEPREVArticleSynthesis and structure of chromium antimony triselenide (CrSbSe3): a pseudo-one-dimensional ferromagnetDebra A. Odink, Veronique Carteaux, Christophe Payen, and Guy OuvrardCite this: Chem. Mater. 1993, 5, 2, 237–240Publication Date (Print):February 1, 1993Publication History Pu…
Stoichiometric mullite, 3Al 2 O 3 ·2SiO 2 , has been prepared from a variety of colloidal and solution precursors. In order to change the level of mixing, the size of the silica particles has been varied while keeping the alumina (boehmite) particle size constant. The effect of varying particle size on the crystalliza…
The stability of the electrical and optical properties of dual ion beam sputtered zinc oxide films, with resistivities of 10−3 Ω cm, were investigated. ZnO films were deposited at room temperature by argon ion beam sputtering of a zinc oxide target. Argon or hydrogen/argon mixtures of positive ions were irradiated by…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSyntheses and characterization of dichlorozirconium porphyrin complexes and their novel organometallic derivatives. X-ray structure of Zr(TPP)Cl2(THF)Hee Joon Kim, Dongmok Whang, Kimoon Kim, and Youngkyu DoCite this: Inorg. Chem. 1993, 32, 3, 360–362Publication Date (Print):…
Superconducting thin films of Sn-doped In2O3 with high visible transmittances were prepared by electron-beam evaporation on polyester and glass substrates, followed by post-deposition annealing. Effects of annealing on electrical and optical properties were examined and optimum conditions under which superconductivity…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFunctionalization of p-tert-butylcalix[6]arene by alkylation with 2-(chloromethyl)pyridine hydrochloridePlacido Neri and Sebastiano PappalardoCite this: J. Org. Chem. 1993, 58, 5, 1048–1053Publication Date (Print):February 1, 1993Publication History Published online1 May 200…
Raman spectra of olivines along the forsterite-monticellite (Fo-Mo) join have been measured in the region of 100-1200 cm-' with a multichannel micro-Raman spectrometer. In the spectrum of Fo, strong Si-Osymmetric stretching bands appear at 824 and at 855 cm-r, and a medium-intensity antisymmetric Si-O stretching band…
Two microscopic methods for characterizing the maturity of a cotton sample have been developed, using either cross-sectional or longitudinal scanning of fibers by image analysis. This study compares the two methods for consistency with the aim of opti mizing their efficiency and accuracy as reference methods. Longitud…
The grain size‐microcracking relation was examined for low thermal expansion NaZr 2 (PO 4 ) 3 family ceramics. By measurements of the strength, Young's modulus, thermal expansion, and grain size of polycrystalline ceramics sintered at appropriate conditions, the critical grain size for microcracking was determined. Th…
X-ray-diffraction studies carried out on Tb0.27Dy0.73Fe2−xCox (x=0,0.5,1.2,2.0) revealed that all compositions investigated retained the C-15 cubic Laves phase structure. Magnetization and electrical resistivity measurements were carried out in the temperature range 77–800 K. Anomalies observed in the resistivity meas…
The change in the visible spectra of some irradiated ternary borate glasses containing chromium has been studied by increasing the γ‐ray doses with changing alkali content or increasing chromium concentration. In the glass without chromium, the γ‐rays induce two absorption bands which are attributed to the formation o…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDependence of the transitional properties of polystyrene-based side-chain liquid-crystalline polymers on the chemical nature of the mesogenic groupC. T. Imrie, T. Schleeh, F. E. Karasz, and G. S. AttardCite this: Macromolecules 1993, 26, 3, 539–544Publication Date (Print):Fe…
Long‐range‐oriented liquid‐crystalline polymers (LCPs) can exhibit anisotropic mechanical, optical, electrical, and magnetic properties. The macroscopic orientation of LCPs proceeds relatively slowly and incompletely compared to low molecular weight liquid crystals. Here, the photopolymerization of thin films of nemat…