Materials Literature
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Mechanisms of thermoluminescence (TL) in aragonite have been studied using electron spin resonance (ESR) techniques. Natural aragonite shows a prominent TL glow peak at 613 K. Additional gamma irradiation enhanced this glow peak but displaces it slightly to 593 K, and induces two glow peaks at 393 and 493 K. Pre-annea…
When co-doped with La 3+ , Ba 3 (PO 4 ) 2 :Eu 2+ shows an intense thermally stimulated luminescence after X-ray irradiation. The phosphor is also optically stimulable. The stimulated emission is due to the Eu 2+ ion. In the absence of Eu 2+ a broad emission band is observed which is tentatively ascribed to a phosphate…
The authors used dynamic mechanical and dielectric thermal analyses together with infrared spectroscopy to identify molecular motions in polyaniline films cast from emeraldine base powder dissolved in the solvent N-methyl-2-pyrrolidinone (NMP). These relaxations include a librational ring motion at around -80 degrees…
The predicted rates of rise of water in glass capillaries of diameters 0.2 and 0.4 mm by a theory which includes the effect of inertia on the movement of the liquid are in satisfactory agreement with experimental data. With an immersion depth (dip length) in the liquid of about 3 mm at the commencement of wicking, the…
The synthesis of luminescent nanometer-scale Si clusters by spark ablation from a crystalline Si substrate is described. The cluster source, described in the text, generates clusters in a flowing Ar stream at atmospheric pressure. Electron microscopy reveals that the clusters have diameters in the 2–4 nm size range. T…
We investigate the stability, bonding, and geometric structure of recently discovered metallocarbohedrenes by the use of density-functional calculations. It is found that the previously proposed ${\mathit{T}}_{\mathit{h}}$ dodecahedron structure is dynamically unstable. Instead, a new, stable, and more strongly bound…
A new technique for the preparation of light emitting nanocrystalline (nc) silicon by a combination of plasma chemical vapor deposition and post-treatment consisting of oxidation and annealing in forming gas is reported. The advantage of this processing consists in the possibility of a control of the crystallite size…
Abstract By condensation of croconic acid ( 7 ) with 2‐(dialkylamino)‐thiophenes 6a – d and with 3‐(dialkylamino)phenols 9a – c the deeply colored, sparingly soluble croconic acid dyes (“croconines”) 8a – d and 10a – c , respectively, have been prepared. These croconines have been characterized by UV/Vis, IR, and 1 H‐…
Films of diblock copolymers with thicknesses less than a lamellar period on a noninteracting surface were found to be model systems for studying the late stages of two dimensional phase separation. It was found under conditions of constant surface coverage that the average particle size 〈R(t)〉, the inverse of the tota…
A combination of electron paramagnetic resonance and band structure calculations is used to show that the Pb2+ ions in lead zirconate titanate materials can act as shallow hole traps to give Pb3+ centers. The Pb3+ centers are created by optical illumination and are found to be metastable at room temperature. Their dec…
High coercivity, c-axis randomly in-plane oriented barium hexaferrite thin films have been successfully fabricated by using conventional rf diode sputtering and post-deposition annealing. Coercivities as high as 4100 Oe have been achieved. Ms, Sq, S*, SFD, and SFDr reach the values of about 270 emu/cc, 0.63, 0.90, 0.1…
The partial radial distribution functions g alpha beta (r) and partial structure factors S alpha beta (k) obtained in computer simulations of the ionic melts of stoichiometry MCl 2 with a recently introduced polarizable ion model are described. The calculated quantities exhibit distinctive structural features which ha…
Minimizing a Euclidean distance in the complex plane optimizes a wide class of correlation metrics for filters implemented on realistic devices. The algorithm searches over no more than two real scalars (gain and phase). It unifies a variety of previous solutions for special cases (e.g., a maximum signal-to-noise rati…
Recent progress in regioselective and enantioselective epoxidations catalyzed by metalloporphyrins is discussed here, with an explanation of the biomimetic antecedents of this area and its relevance to synthetic applications. Classification of the catalysts that have been studied allows useful conclusions to be drawn…
Terfenol-D is a magnetostrictive material with properties such as large strain, high force, wide bandwidth, and high energy density. Terfenol-D actuator, with its unique characteristics, is therefore potentially a new class of actuator most suitable for embedded actuator applications. This paper deals with the modelli…
The possibility of using interdigitated surface electrode patterns to improve the transverse actuation capability of electroceramic actuators is investigated. This pattern produces nonuniform electrical fields in the plane of the wafer which utilize the longitudinal piezoelectric effect to generate larger, more anisot…
The authors present results from electronic structure calculations of the intermetallic hydrides M 2 M'H 6 (M=Mg, Ca, Sr, M'= Fe, Ru, Os). Most of these hydrides have been recently synthesized and characterized, all showing the K 2 PtCl 6 cubic structure. They have determined their energy bands and densities of electr…
A dipole particle suspension device was fabricated by sandwiching rodlike TiOxNy particles dispersed in a poly(dimethylsiloxane) derivative between two indium-tin-oxide coated glass substrates. On applying and removing an electric field of 2 kV mm−1 with a frequency of 200 Hz, a reversible solar transmittance change a…
Common optical absorption features are observed near 0.5 eV in four undoped single-crystal copper oxides: ${\mathrm{La}}_{2}$${\mathrm{CuO}}_{4}$, ${\mathrm{Nd}}_{2}$${\mathrm{CuO}}_{4}$, ${\mathrm{Pr}}_{2}$${\mathrm{CuO}}_{4}$, and ${\mathrm{Sr}}_{2}$${\mathrm{CuO}}_{2}$${\mathrm{Cl}}_{2}$. These absorption bands are…
Abstract Interaction between polypropylene matrix and carbon black was examined by measuring physical, mechanical, and electrical properties. It has been shown that presence of carbon black influences the morphology and crystallinity of the matrix. Strong interaction was observed directly by electron microscopy and in…