Materials Literature
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Local icosahedral order is found to increase as random hard-sphere packings (one- and two-component) generated on the computer are densified from the (recently established) ``loose random-packing'' limit to the ``dense random-packing'' limit. While icosahedral ordering in ``atomic'' systems is frequently ascribed to t…
Abstract Nylon 6–clay hybrid is a molecular composite of nylon 6 and uniformly dispersed silicate layers of montmorillonite. One‐pot synthesis of the hybrid was carried out by the following procedures. Montmorillonite was dispersed in water, and then ε‐caprolactam, acid (phosphoric acid, hydrochloric acid, benzenesulf…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHydrolysis of tri-tert-butylaluminum: the first structural characterization of alkylalumoxanes [(R2Al)2O]n and (RAlO)nMark R. Mason, Janna M. Smith, Simon G. Bott, and Andrew R. BarronCite this: J. Am. Chem. Soc. 1993, 115, 12, 4971–4984Publication Date (Print):June 1, 1993P…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-aggregates of hydrophobized polysaccharides in water. Formation and characteristics of nanoparticlesKazunari Akiyoshi, Shigeru Deguchi, Nobuhiro Moriguchi, Shigehiko Yamaguchi, and Junzo SunamotoCite this: Macromolecules 1993, 26, 12, 3062–3068Publication Date (Print):J…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-orienting head-to-tail poly(3-alkylthiophenes): new insights on structure-property relationships in conducting polymersRichard D. McCullough, Stephanie Tristram-Nagle, Shawn P. Williams, Renae D. Lowe, and Manikandan JayaramanCite this: J. Am. Chem. Soc. 1993, 115, 11,…
Under appropriate conditions of concentration and ionic strength, trans-bis(N-methylpyridinium-4-yl)-diphenylporphine and its copper(II) derivative produce very large, bisignate circular dichroism signals in the Soret region when bound to DNA. The processes leading to these signals are shown to be highly cooperative.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTArtificial photosynthesis. 1. Photosensitization of titania solar cells with chlorophyll derivatives and related natural porphyrinsAndreas Kay and Michael GraetzelCite this: J. Phys. Chem. 1993, 97, 23, 6272–6277Publication Date (Print):June 1, 1993Publication History Publis…
Abstract The sol–gel process, with its associated mild conditions, offers a new approach to the synthesis of composite materials with domain sizes approaching the molecular level. Transparent organic–inorganic composites can be prepared by dissolving preformed polymers into sot–gel precursor solutions, and then allowi…
An automatic procedure for recovering a complete crystal structure after a direct phasing process is described. The procedure consists mainly of a Fourier recycling method that can be implemented in any direct-methods package. The residual R value attained at the end of the process provides an estimate of the degree o…
Co 2+ enters the lattice of zirconia stabilized with a 46% of yttria in fourfold coordinated cation sites. The absorption spectrum consists mainly of two triplets, one of which is rather weak at around 5500 cm -1 (corresponding to the 4 A 2 to 4 T 1 ( 4 F) transition), while the other is very intense at around 15175 c…
Sintering characteristics of Sm2Fe17Nx were studied under high-pressure conditions (pressure=3 GPa and temperatures=300, 550, and 800 °C) without any binding material. High-pressure treatments at 3 GPa and 550 °C succeeded in preparing the sintered materials without any decomposition, which possessed density values cl…
The use of heteropolycompounds (heteropolyacids and their salts) as acid and oxidation catalysts of fine organic synthesis reactions is examined. The use of the heteropolycompounds in the synthesis of antioxidants, medicinal preparations, vitamins and other products produced on a small scale is discussed. Examples of…
A metal-semiconductor-metal (MSM) photoconductor and a p-n photodiode have been fabricated from rapid-thermal-oxidized (RTO) porous Si. The MSM photoconductor achieved 2.8×higher responsivity at 350 nm than a UV-enhanced Si photodiode, and the RTO photodiode exhibited an external quantum efficiency of 75% at 740 nm.
Yttria-stabilized cubic zirconia has been studied at 300 K by use of Raman spectroscopy under uniaxial stress along the [001] and [111] directions. The main effects observed are the frequency shifts of the F2g-type Raman band at ∼610 cm−1 which vary linearly with the applied stress and tend to increase with Y2O3 conce…
A set of extra peaks, which dominate the region of the silver s-p band, are observed in angle-resolved photoemission from Ag islands formed on GaAs(110) by low temperature deposition and annealing to room temperature. The thickness dependence of peak spacing demonstrates that the new peaks originate from wave vector q…
Samples of nanocrystalline Ge embedded in SiO2 that display visible photoluminescence were synthesized from chemical vapor deposition-grown Si0.6Ge0.4 in a two step process of hydrothermal oxidation using steam at 25 MPa and 475 °C followed by annealing at 750 °C in flowing forming gas (80/20:N2/H2). A broad photolumi…
Inelastic scattering of electrons in solids is computed from a generalized oscillator strength model based on optical and photoelectric data. The optical oscillator strength is extended into the non-zero momentum transfer region by using free-electron gas dispersion for the weakly bound electrons. The applicability of…
A process for forming porous SiC from single-crystal SiC wafers has been demonstrated. Porous SiC can be fabricated by anodizing n-type 6H-SiC in HF under UV illumination. Transmission electron microscopy reveals pores of sizes 10–30 nm with interpore spacings ranging from ≊5 to 150 nm. This is the first reported dire…
By measuring the complex dielectric function over 15 decades in frequency we evaluate the scaling of the \ensuremath{\alpha}-relaxation for several glass-forming liquids including propylene carbonate. The temperature dependence of the mean relaxation time and of the relaxation strength of the relaxation function displ…
We have observed a new type of magnetic linear dichroism in angle-resolved, spin-integrated photoemission: For p-polarized light under oblique incidence the Fe 3p core level peak position and line shape change when the sample magnetization is reversed. Spin-resolved measurements show that the effect is due to spin-orb…