Materials Literature
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The glass transformation temperature, thermal expansion coefficient, dc electrical conductivity, and IR transmission have been measured for four series of lead halosilicate glasses of the general composition (65– x )PbO· x PbX 2 ·35 SiO 2 (X=F, Cl, Br, I). Although results of these and other measurements suggest that…
A novel method of calibrated doping of Mn in ZnS thin films has been used to study room-temperature cathodo- and photoluminescence characteristics of ZnS:Mn films for a Mn concentration range of 0.07–26.4 wt. %. It was observed that the luminescent intensity increases with Mn concentration up to ∼2 wt. %, beyond which…
A simulation model of the microstructure developed during the reaction sintering of ultrafine silicon powders is presented. The model employs interactive subroutines that describe particle compaction, sintering, and nitridation. The particle compaction model is based on a random particle packing model, whereas the sin…
The anchoring properties of the director at the interface between a nematic LC and an isotropic substrate are discussed. More emphasis is devoted to the special cases of the nematic LC free surface and of the nematic-isotropic interface. Some recent theoretical models for these interfaces are briefly discussed and the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolybdenum and tungsten complexes with unusual coordination modes of a dibenzotetraaza[14]annulene ligand. From bidentate to tridentate scorpiand coordination by reaction with acetonitrile and from bidentate to tetradentate coordination via electrochemistryJean Marc Giraudon…
Summary To establish a relationship between the molecular structure of polycarboxylates and their growth-retarding influence on barium sulfate, seeded-suspension-growth experiments were performed at various inhibitor concentrations and pH values. Two types of polycarboxylates with a molecular structure based on either…
The extinction factor in finite perfect crystals is calculated from pure dynamical theory. In particular, a detailed solution is proposed for a sphere, in which case the extinction factor depends on the Bragg angle θ and the parameter ( R / Λ ), where R is the radius of the crystal and Λ the extinction length. An appr…
Large oscillations in the vibrational Raman intensity have been observed for thin films adsorbed on a metal substrate as a function of film thickness. The systems studied, N2 and O2 physisorbed on Ag(111) at 14±1 K, have previously been shown to be unenhanced, i.e., the observations are not caused by the surface enhan…
We report the observation of optical nonlinearities induced by thermal effects in polymer dispersed liquid crystals. Experimental data about optical switching of a low power laser beam are presented and discussed
ABSTRACT New UK regulations from June 1989 will enforce the provisions of an EC Directive on the use of sewage sludge in agriculture. Among the requirements is one that sludge should be treated before surface application to farmland. Treatment is needed to reduce ‘significantly’ both the fermentability of sludge and t…
The effect of powder characteristics on the microstructures and dieletric properties of (Ba,Nb)‐doped TiO 2 ceramics was investigated. Two powders were prepared: one by coprecipitation and the other from mixing of reagent oxides. The powder characteristics were determined by TEM, X‐ray powder diffraction, SEM, and cen…
Mixed oxides of copper and aluminum were prepared in porous form by the citrate process under various calcination conditions. The oxide samples were characterized by several techniques to determine chemical structure and texture. Atomic absorption spectroscopy provided the fractions of copper soluble and insoluble in…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDirect metalation of p-bromopolystyrene using highly reactive copper and the preparation and reaction of highly reactive copper bound to an insoluble polymerRichard A. O'Brien and Reuben D. RiekeCite this: J. Org. Chem. 1990, 55, 3, 788–790Publication Date (Print):February 1…
The oxidation of iron in gas mixtures consisting of Ar, , and at 1100 and 1200 K has been investigated by thermogravimetric analysis and examination of the corrosion products of the process by scanning electron microscopy and x‐ray diffraction analysis. The results of the experiments have been compared with theoretica…
Zinc oxide (ZnO) thin films have been prepared by a sputtering deposition utilizing electron-cyclotron-resonance (ECR) plasma. An X-ray diffraction analysis indicated that the ZnO films were highly c -axis oriented. The electrical resistivity of ZnO films is as high as 2.5 MΩcm. It is confirmed that the ZnO films exhi…
A series of electron diffraction patterns displaying continuous transformation of the octagonal quasicrystal into the β-Mn type structure were obtained in a rapidly quenched Cr-Ni-Si alloy. This transformation is interpreted in terms of a gradual introduction of short-range periodical translational order to the octago…
A clean silver island film prepared in UHV was covered at about 28 K first with one monolayer of C 5 D 5 N and afterwards exposed to a quantity of C 5 H 5 N corresponding to 4 monolayers (or vice versa ). Raman scattering showed an intensity enhancement of about 2 orders of magnitude confined to the isotopic species a…
The activity of rhodium for oxygen gas evolution in base is significantly enhanced by the presence of a thick, hydrous oxide film which is produced by repetitive potential cycling. An increase in oxygen evolution rate of up to three orders of magnitude was obtained on growing these films; the latter were found to be s…
Fluoride salt mixtures of composition, LiF–BeF2–ZrF4–UF4 (64.5, 30.3, 5.0, 0.13 mol%) were irradiated using 107–108 R/h gamma radiation to achieve high doses. Under these conditions, F2 is released from the salt and accumulates as an F2 overpressure until a 2 mol% damage limit in the crystal is reached. At this point,…
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