Materials Literature
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The preparation of CeO 2 thin films on sapphire by DC reactive magnetron sputtering of metallic Ce target in an argon-oxygen mixed gas is reported. The resputtering of the film deposited facing the target track was observed. The films deposited far from the sputtering system axis exhibited well-oriented crystalline st…
The effect of sulphur addition on some structural properties of a-Se was studied for compositions up to about 30 at.% S. The sulphur in the binary amorphous semiconductor system Se-S was found to affect the density (d), microhardness (VH), dielectric constant ( in ) and tendency to crystallization (T c -T g ), as well…
Data are reported on the luminescence spectra generated by X-ray and electron irradiation of optical fibres, fibre preforms and silica. The impurities and imperfections in the fibre core have a higher luminescence efficiency than those in the substrate material. The core luminescence provides a major fraction of the t…
The electronic and geometrical structures of exchange-coupled open-shell systems such as bis(methylene) methane and the chromium–methylene cation were investigated by the molecular orbital and its extended methods: RHF, UHF, UNO-CAS, RMP, UMP, PUMP, APUMP, UCCSD(T), UNO-CI and QCISD(T). The fully optimized geometries…
Sputtering of highly oriented pyrolytic graphite (HOPG) by 248-nanometer laser radiation was studied. Neutral carbon atoms and small clusters were ejected with significantly higher translational energies than were expected from a simple model of thermal vaporization in the absence of a potential barrier. The HOPG also…
As diamond-producing catalysts, 12 transition metals such as iron, cobalt, and nickel were first reported by General Electric researchers more than 30 years ago. Since then, no additional elemental catalyst has been reported. An investigation of the catalytic action of group V elements is of great interest from the vi…
Transmission electron microscopy (TEM) observations of graphite tubules (buckytubes) and their derivatives have revealed not only the previously reported buckytube geometries but also additional shapes of the buckytube derivatives. Detailed cross-sectional TEM images reveal the cylindrical cross section of buckytubes…
Very complicated inorganic solids can be self-assembled from structurally simple precursors as illustrated by the hydrothermal synthesis of the vanadium phosphate, [(CH(3))(2)NH(2)]K(4)[V(10)O(10)(H(2)O)(2)(OH)(4)(PO(4))(7)].4H(2)O, 1, which contains chiral double helices formed from interpenetrating spirals of vanadi…
Abstract Starch‐ g ‐poly(methyl acrylate) (S‐ g ‐PMA) copolymers containing 55–60% PMA were prepared from cornstarch, high amylose cornstarch, and waxy cornstarch with ceric ammonium nitrate initiation. Graft copolymers were characterized with respect to % PMA homopolymer, % conversion of monomer to polymer, grafted P…
Abstract The effect of diethylene glycol (DEG) on the crystallization of poly(ethylene terephthalate) (PET) was studied under isothermal and dynamic conditions. The strain‐induced crystallization of PET and its relationship to DEG content was also studied. The samples were isothermally and dynamically crystallized in…
Abstract Sisal fibers (Agave‐Veracruz) have been used as reinforcements in low‐density polyethylene (LDPE). The influence of the processing method and the effect of fiber content, fiber length, and orientation on tensile properties of the composites have been evaluated. The fiber damage that normally occurs during ble…
The angular dependences of the free energy, thickness and stresses are calculated for the antiphase boundaries (APBS) parallel to the tetragonal z axis but otherwise arbitrarily oriented. The general results are applied to Hg 2 Br 2 and KSCN. The APB in the former case is shown to decay into two ferroelastic domain wa…
Abstract The crystal growth behaviour of the important organic nonlinear optical material 2-(a-methylbenzylamino)-5-nitropyridine (MBANP) (space group P21) has been investigated and techniques have been developed for the preparation of large (up to 7 cm x 4 cm x 3 cm) high-quality single crystals suitable for detailed…
The influence of grain boundary scattering of lattice waves in high quality diamond films has been determined by the measurement of thermal conductivity down to 0.15 K. We find that the mean free path for lattice vibrations (phonons) exceeds substantially the crystallite size and approaches the physical size of the sa…
The cross-luminescence (CRL) resulting from radiative electronic transitions from the mainly anion-related valence band to the uppermost cation core band has been studied in a number of complex halides containing CsCl, RbF, KF, and BaF 2 . The energy of the CRL photons is determined by the energy difference of the two…
We report novel biphotonic holographic storage of text and gratings on unoriented films of a side-chain liquid crystalline polyester capable of high density storage and complete erasure. The holograms have a typical size of 1 mm. The recording utilizes unusual photochemistry involving azo dye molecules. We believe tha…
Polyethylene propylene films of various molecular weights, which would normally wet native-oxide-covered Si surfaces, were observed to dewet the surface when the film thickness became less than the polymer radius of gyration. These films could be made to wet either by increasing the annealing temperature or by chemica…
Polycrystalline thin films of Ba0.5Sr0.5TiO3 were deposited by excimer laser (248 nm) ablation. Films deposited near 575 °C exhibited good crystallinity, a dielectric constant of 330, a dissipation factor of 0.02, a leakage current density of 2×10−7 A/cm2, a charge storage density of 36 fC/μm2, and breakdown time of 3…
FTIR spectra reported by Brandt et al. [Solid State Commun. 81, 307 (1992)], Tischler et al. [Appl. Phys. Lett. 60, 639 (1992)], and Tsai et al. [Appl. Phys. Lett. 59, 2814 (1991), and 60, 1700 (1992)] have shown the presence of Si-H and Si-H2 lines in porous Si which Canham [Appl. Phys. Lett. 57, 1046 (1990)], Tischl…
A boiling water treatment of light emitting porous silicon can give rise to a large blue shift of its photoluminescence spectrum and meanwhile strengthen the skeleton of porous Si by filling up many pores with aqueous oxide. A stable blue-green light emission at the peak wavelength down to 500 nm is achieved. FTIR mea…