Materials Literature
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We describe a systematic method for obtaining the coupling coefficients due to diffraction orders less than the grating order of second- and higher order resonant complex gratings in a multilayer structure. This method is based on an improved Green's function, and its distinguishing feature is its use of the transfer…
Sensibilisierte Nah-Infrarot-Lumineszenz (NIR-Lum.) wurde bei Lanthanoiden (Ln) erstmals beobachtet (siehe Schema; Exc.=Anregung). Ermöglicht wurde dies durch Energietransfer (ET) von Ferrocen- oder Tris(bipyridin)ruthenium-funktionalisierten lichtsammelnden Einheiten. Dank der Luminszenz des Triplettzustands des Ru-D…
A full analysis of thermal motion has been carried out for the negative thermal expansion material Sc 2 (WO 4 ) 3 over the temperature range 50−823 K. By obtaining neutron diffraction data from isotopically pure samples of the compositions Sc 2 ( 184 WO 4 ) 3, Sc 2 ( 186 WO 4 ) 3 and natural Sc 2 (WO 4 ) 3, coupled wi…
Polycarbosilane‐derived SiC fibers (Nicalon) were oxidized at 1773 K under oxygen partial pressures from 10 2 to 10 5 Pa. The effect of oxygen partial pressure on the oxidation behavior of the Nicalon fibers was investigated by examining mass change, surface composition, crystal phase, morphology, and tensile strength…
Some thiourea derivatives, non‐ionic surfactants and their synergism when used simultaneously were evaluated for their efficiency as corrosion inhibitors for mild steel in 1N H 2 SO 4 solution at different temperatures (303, 313 and 323K). A marked inhibition synergism occurred within an optimum concentration range ev…
Electrochemical noise behavior of Type 304 austenitic stainless steel (UNS S30400) with various degrees of sensitization was investigated under slow strain rate tensile (SSRT) conditions in a dilute sodium thiosulfate (Na2S2O3) solution. Fluctuations in short-circuit current between a SSRT specimen and a counter elect…
The effect of tolyltriazole (TTA) on the corrosion of Al‐Cu, Al‐Si‐Cu and Al‐Cu‐Fe alloys in HCl (pH = 0.5) and NaCl (pH = 6 and 11) respectively at 15 ○ C, 25 ○ C and 35 ○ C has been studied by electrochemical methods. Corrosion potentials, corrosion rates, polarization resistances, inhibition efficiencies and activa…
The line tension of a dislocation is measured in a vertical smectic-A film as a function of temperature and film thickness. There are two contributions to the line tension: a bulk contribution that corresponds to the energy of the dislocation in an infinite medium and a surface correction that accounts for interaction…
A finite-element full-vectorial beam-propagation method is presented, for the first time, for the analysis of 3-D anisotropic optical waveguides. Full 3/spl times/3 permittivity and permeability tensors are considered. The formulation takes into account the polarization dependence and the component coupling due to the…
A simple method for the fabrication of nanocrystalline Cu 4 O 3 in polyaniline is reported. An aqueous solution of copper(II) acetate and aniline (1:10 mole ratio) is irradiated by ultrasound to produce nanophased Cu 4 O 3 embedded in a polyaniline matrix. The as-prepared Cu 4 O 3 - polyaniline is characterized by X-r…
An inspection technique based on angular dispersive X-ray diffraction (ADXRD) has been developed to chemically specific detection of explosives for screening applications. The technique identifies explosives from benign materials using the characteristic Bragg features seen in coherently scattered X-rays. To implement…
Poly(3-hydroxyalkanoate)s, PHAs, containing pendant carboxyl groups were prepared by the chemical modification of unsaturated PHAs using potassium permanganate (KMnO4) at 55°C, although there is a severe loss in molecular weight of PHAs during the reaction. The introduction of carboxylic groups in the products was ver…
Several previous studies of ${\mathrm{K}}_{1\ensuremath{-}x}{\mathrm{Li}}_{x}{\mathrm{TaO}}_{3}$ (KLT) have revealed the presence, above the structural transition, of polar nanoregions. Recently, these have been shown to play an essential role in the relaxor behavior of KLT. In order to characterize these regions, we…
Photoinduced electron transfer processes between C 60 / C 70 and phthalocyanines such as tetra-tert-butylphthalocyanine ( H 2 TBPc ) and its zinc derivative ( ZnTBPc ) in polar solvents have been studied by observing the transient absorption spectra in the visible and near-IR regions. Upon predominant excitation of TB…
The electrical transport in quasiperiodic systems at zero temperature is studied by means of the Kubo-Greenwood formula within a tight-binding model. Their dc conductivity is compared with that obtained from the Landauer formula. Special attention is paid to the transparent states, whose transmittance is unity. The ac…
Monoclinic and hexagonal forms of celsians (BaAl 2 Si 2 O 8 ) were synthesized by hydrolysis–polycondensation of Si/Al alkoxide mixtures. Dilatometry, Raman scattering, IR absorption, and X‐ray diffraction techniques were used to identify various hexacelsian phases and their conversion into the monoclinic phase as a f…
Phase‐pure perovskite Pb(Zn x Mg 1– x ) 1/3 Nb 2/3 O 3 solid solution (PZ x M 1– x N) is obtained for x ≦ 0.7 by heating a milled stoichiometric mixture of PbO, Mg(OH) 2 , Nb 2 O 5 , and 2ZnCO 3 ·3Zn(OH) 2 ·H 2 O at 1100°C for 1 h. Percent perovskite ( f P ) with respect to total crystalline phase decreases with incre…
Among other soft chemistry processes, sol-gel chemistry offers a versatile access to chemically designed new hybrid organic-inorganic materials. Two approaches to synthesize hybrids are presented: the hydrolysis of organo functional metal alkoxides or the assembly of nanobuilding blocks.
A generalized theory that includes short-range elasticity, long-range elasticity, and flow effects is used to simulate and characterize the shear flow of liquid crystalline materials as a function of the Deborah (De) and Ericksen (Er) numbers in the presence of fixed planar director boundary conditions; the results ar…
Complex particles have been formed by the electrostatic association of protonated polystyrene- b -poly(2-vinylpyridine) (PS- b -PVPH + ) micelles with sodium poly(styrenesulfonate) (PSS - Na + ), all at pH 1. Light scattering demonstrates that there is a large mass excess of PSS - associated with each PS- b -PVPH + mi…