Materials Literature
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Highly-oriented zinc oxide (ZnO) films were grown on quartz glass substrates by radio frequency magnetron sputtering method. The temperature dependence of the photoluminescence spectra of the ZnO films annealed in argon, argon mixed with 5% hydrogen (H2/Ar) and oxygen ambient, respectively, was investigated from −190…
We have studied spin freezing in the diluted spin ice compound Dy2-xYxTi2O7 where the non-magnetic Y ions replace the magnetic Dy ions on the frustrated pyrochlore lattice. Magnetic a.c. and d.c. susceptibility data are presented with an analysis of relaxation times for dilutions of x = 0, 0.1, 0.2, and 0.4. Site dilu…
Photoluminescent porous silicon (PSi) was produced by Pt-assisted electroless etching of p−-Si (100) in a 1:2:1 solution of HF, H2O2, and methanol. The peak emission wavelength of the PSi could be tuned in the range 500 nm⩽λ⩽600 nm simply by changing the time of etching. The luminescence is sufficiently intense at all…
Nanocrystalline nickel ferrite (NiFe2O4) particles were successfully synthesized in situ in an amorphous silica matrix by mechanical activation at room temperature. Phase development in the amorphous precursors, derived via a modified sol–gel synthesis route, with increasing mechanical activation time was studied in d…
Anderson-type molybdopolyanions containing tris(alkoxo) ligands [MMo6O18{(OCH2)3CR}2]3− (M = MnIII, FeIII) and [H2MMo6O18{(OCH2)3CR}2]2− (M = NiII, ZnII), (R = CH3, NO2, CH2OH), were prepared by treatment of [N(C4H9)4]4[α-Mo8O26] with tris(hydroxymethyl)methane derivatives in the presence of manganese(III) acetylaceto…
Systems of classification are not hat racks, objectively presented to us by nature. They are dynamic theories developed to express particular views about the history of organisms. Evolution has produced a set of unique species ordered by differing degrees of genealogical relationship. Taxonomy, the search for this nat…
Materials science has emerged as one of the central pillars of the modern physical sciences and engineering, and is now even beginning to claim a role in the biological sciences. A central tenet in the analysis of materials is the structure-property paradigm, which proposes a direct connection between the geometric st…
This article presents an analysis of the response of silicon carbide to high velocity impact. This includes a wide range of loading conditions that produce large strains, high strain rates, and high pressures. Experimental data from the literature are used to determine constants for the Johnson–Holmquist constitutive…
The behavior of light-emitting electrochemical cells (LEC) based on solid films ( approximately 100 nm) of tris(2,2'-bipyridine)ruthenium(II) between an ITO anode and a Ga-In cathode was investigated. The response times were strongly influenced by the nature of the counterion: small anions (BF(4)(-) and ClO(4)(-)) led…
Marine snow is a ubiquitous feature of the ocean and an important agent in the transport of energy and nutrients through marine ecosystems. Diatom aggregates, which form during blooms and, to a lesser extent, by the resuspension of benthic biofilms, are a primary source of marine snow. Genera commonly found in diatom…
The kinetics of the epoxidation of soybean oil and the extent of side reactions were studied at 40, 60, and 80 °C. Epoxidation was carried out in toluene with “in situ” formed peroxoacetic and peroxoformic acid and in the presence of an ion exchange resin as the catalyst. The reaction was found to be first-order with…
Hydrotalcite was synthesized by a homogeneous precipitation method utilizing urea hydrolysis. When the homogeneous aqueous solutions containing magnesium chloride, aluminum chloride, and urea were heated, hydrotalcite particles were obtained. Scanning electron micrographs revealed that the products were well-defined h…
Rare‐earth‐doped oxynitride or nitride compounds have been reported to be luminescent and may then serve as new phosphors with good thermal and chemical stabilities. In this work, we report the photoluminescence (PL) spectra of europium‐, terbium‐, and praseodymium‐doped Ca‐α‐SiAlON ceramics. The highly dense ceramics…
Author: Douglas B. Murphy Bibliographic Data: John Wiley & Sons, Inc., 2001. ISBN: 0-471-25391-X, NLM: QH 211, 368 pp, hard cover, $79.95. Reviewer's Expert Opinion: Description: This book on the use of the light microscope introduces all of its classical and modern techniques and applications. It provides thorough th…
Abstract The use of in situ Raman spectroscopy to study the molecular structures of supported metal oxide catalysts under different environments is reviewed. The molecular structures under ambient (hydrated) and dehydrated conditions are presented. The effect of moisture at elevated temperatures is also presented and…
Stereoselective polymerization of racemic lactide (rac-LA) was examined using Al-achiral ligand complexes. By introduction of substituents in aromatic rings of Schiff base ligands, a higher selectivity was obtained without any chiral auxiliaries in the catalyst via a chain-end control mechanism. The T(m) values (T(m)…
The difference in the local environment of CO 3 2- , NO 3 - , SO 4 2- , and ClO 4 - in Mg/Al-hydrotalcite compared to the free anions was studied by infrared and Raman spectroscopy. In comparison to free CO 3 2- a shift toward lower wavenumbers was observed. A band around 3000-3200 cm -1 has been attributed to the bri…
DL_POLY is a general-purpose molecular dynamics simulation package, which was developed by Daresbury Laboratory in the mid-1990s for the molecular simulation community in the United Kingdom. The package now has a world-wide user base and applications in many areas of molecular simulation. In this article we briefly re…
Carbon nanotubes were grown directly on carbon fibers using chemical vapor deposition. When embedded in a polymer matrix, the change in length scale of carbon nanotubes relative to carbon fibers results in a multiscale composite, where individual carbon fibers are surrounded by a sheath of nanocomposite reinforcement.…
Despite the extraordinary promise of single-wall carbon nanotubes, their realistic application in materials and devices has been hindered by processing and manipulation difficulties. Now that this unique material is readily available in near kilogram quantities (albeit still at high cost), research into means of chemi…