Materials Literature
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Copper-doped SrTiO/sub 3/ (STO) powders were processed by conventional bulk preparation techniques to establish solubility limits of Cu in STO. The maximum solubility of Cu in STO was identified to be /spl sim/1%. Epitaxial Cu-doped SrTiO/sub 3/ (STO) buffer layers were then prepared by pulsed laser deposition (PLD) a…
The helical structure of the chiral nematic phases induced by chiral dopants in nematic solvents provides macroscopic information about the molecular chirality of the dopant. The surface model, which combines the order parameters of the dopant in nematic host phase and chirality parameters of the dopant, is a simple m…
M-Si-Al-O-N glasses (where M = Y or rare earth cation) are intergranular phases in silicon nitride based ceramics in which the composition and volume fraction of these oxynitride glass phases determine the properties of the material, in particular, high temperature mechanical behaviour. Investigations on oxynitride gl…
Dye-doped Liquid Crystals (LCs) are very attractive materials for many applications (Optically Addressed Spatial Light Modulators, dynamic holography, all-optical switching) because of their high sensitivity to optical fields, possibility of use in transmission and low cost. The complexity of the physical effects (sur…
The effects of chloride and phosphoric acid (H3PO4) on the corrosion of Alloy C-276 (UNS N10276), UNS N08028, and UNS N08367 have been studied using electrochemical techniques. All of these alloys are widely used in the chemical process industries because of their excellent corrosion resistance in the severe service c…
The spontaneous and stimulated UV luminescence spectra of ZnO:N samples possessing different nitrogen contents are measured at a temperature of 77 K. Luminescence peaks resulting from bound and free excitons, biexcitons, and electron recombination via the nitrogen acceptor level are identified. The optical depth (123…
The industrial demand for gold has remained relatively static over the past decade and is a small proportion of total gold demand. Current applications are briefly reviewed and the prospects for future growth discussed. It is evident that substantial growth in demand will come only from the development of new applicat…
An optical microscopy investigation of the SmA phase close to the nematic phase puts into evidence the interaction between focal conic domains on one hand, screw and edge dislocations on the other hand. We report here three different situations of such interactions. Our results point towards a dislocation model of the…
A single-shot optical pump-and-probe test system is reported. The system is designed for thermal characterization of thin-film samples that can change their phase state under the influence of a short and intense laser pulse on a subnanosecond time scale. In combination with numerical analysis, the system can be used t…
We have developed a gas sensor for hydrocarbons using layered structures hydrocarbons/porous silicon. Sensitivity of this device, response time and capacitance response to different gases (ethane, ethylene and propane) have been studied. DC and AC electrical measurements were performed to test the sensor and it has be…
Óxido de cério com partículas de tamanho nanométrico foi preparado pela técnica da precipitação utilizando como agente precipitante o hidróxido de amônio ou o ácido oxálico. O principal objetivo deste trabalho foi a obtenção de pós nanométricos de CeO2 com altos valores de área de superfície específica. Os pós calcina…
We propose a novel microlens array structure in a homeotropic liquid crystal (LC) configuration. The symmetry of molecular ordering in the homeotropic alignment on a circular surface relief structure provides the polarization independent focusing characteristics of the LC microlens. The surface relief structure of pol…
Reactions between a tripodal trithiaether-triamine and the monomethoxycarbonylmethyl ether of p-tert-butylcalix[4]arene led to the ready isolation of both di- and triamides, namely di- and tricalixaryl derivatives of the tripod. These molecules, designed as dendrimer precursors, retain a core capable of acting as a mu…
In this experimental study, the effects of pile length on abrasion resistance of chenille fabrics were investigated. In order to monitor the effect of pile length, we produced chenille yarn samples with different pile lengths of 0.7, 0.8, 1, 1.2 mm and wove them into upholstery fabric. Then, the fabric samples were su…
In order to investigate the reciprocal interaction between a SFCL and the Power System an equivalent circuit of the device needs to be introduced in a power system simulator. In this paper the equivalent circuit of a magnetic shield type SFCL, consisting of two coupled electric and thermal networks, is obtained starti…
Abstract Absorption of infrared radiation in the porous silicon (PS) films prepared by common electrochemical etching in DF‐ethanol‐D 6 solutions was studied. We report our results of the effect of deuterium termination on the process of surface states changes of the PS after their exposure to ambient air for few mont…
The luminescent properties of Er 3+ ions embedded in silicate glass matrices with F, N, K, Al, P, Ge, P + Al, P + K, and Ge + Al admixtures are studied. Glass samples with an erbium concentration of up to 9 × 10 20 cm −3 are synthesized by plasma-assisted CVD. The spectra, kinetics, and relative quantum efficiency of…
A family of meta octa-substituted 5,10,15,20-tetraphenylporphyrin derivatives and their metal ( Cu(II) and Zn(II) ) complexes were examined by electrochemical studies. These functionalized MTPPs exhibited a dramatic anodic shift (>200 mV ) in their first ring redox potentials relative to the para-phenyl substituted…
Third-order optical nonlinearities of several polymer films doped with naphthalocyanine derivatives have been measured under resonant conditions by femtosecond degenerate four-wave mixing (DFWM). The metal substitution and the peripheral groups influence both the magnitude and the response of the third-order optical n…
On the Ag(111)-p(4x4)-O surface SO2(g) reacts with oxygen according to SO2(g)+O(a)-->SO3(a). Sulfite forms in a (2 radical3x2 radical3)R30 degrees structure. The restructuring of the surface atoms during sulfite formation is indicative of the deconstruction of the p(4x4)-O structure. Heating the sulfite-covered surfac…