Silicate Glasses
Mostrando 1-7 de 7 artigos, teses e dissertações.
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1. Effect of different approaches to decouple the dependence of nuclei-liquid surface energy on size and temperature
Tests involving the Classical Nucleation Theory (CNT) often disregard the size dependence of surface energy. Thus, the surface energy of critical nuclei is assumed to be a macroscopic quantity that depends only on the temperature of a flat surface. However, because the size of critical nuclei changes with temperature, σcl(T) should be described as a functio
Materials Research. Publicado em: 2009-03
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2. Uso das técnicas de infravermelho e de ressonância magnética nuclear na caracterização da reação ácido-base de um cimento odontológico experimental
Glass ionomer cements (GICs) are products of the acid-base setting reaction between an finely fluoro-alumino silicate glass powder and poly(acrylic acid) in aqueous solution. The sol gel method is an adequate route of preparation of the glasses used to obtain the GICs. The objective of this paper was to compare two powders: a commercial and an experimental a
Química Nova. Publicado em: 2009
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3. Correlation between conductivity and free volume in rubidium and cesium silicate glasses
It is shown that conductivity and molar volume in binary rubidium and cesium silicate glasses, both measured at room temperature, obey a common cubic scaling relation due to increase in alkali content. The drastic drop in conductivity up to 15 orders of magnitude for so many ion-conducting binary alkali silicate glasses (in wide composition range) is mainly
Brazilian Journal of Physics. Publicado em: 2007-06
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4. Test of Anderson-Stuart model and the "universal" conductivity in rubidium and cesium silicate glasses
An analysis and brief discussion of experimental ionic conductivity sigma and activation energy E A in the binary rubidium and cesium silicate systems is presented, exemplified on 23 and 30 glasses respectively, in a wide composition range (5-45 Rb2O and Cs2O mole%). The Anderson and Stuart model has been considered to describe the variation of activation en
Brazilian Journal of Physics. Publicado em: 2005-09
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5. Nanoagregados em matrizes vitreas
In this thesis we studied the formation and growth of nanoclusters in supersa-turated glassy matrixes during isothermal annealing. We investigate: (i) the effects of sulfur content and of a thermal pre-treatment on the formation and growth of CdTe1-x Sx nanocrystals in a borosilicate glass matrix; (ii) the formation and growth of PbTe nanocrystals in a silic
Publicado em: 2003
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6. Electrical conductivity of borate, silicate and silica-sulphate glasses of alkaline ions. / Condutividade elétrica de vidros de boratos, silicatos e sílico-sulfatos de íons alcalinos.
Conducting glasses based on borates, silicates and silica-sulfates of alkali metals have been prepared from an appropriate mixture of powder of oxides, carbonates and sulfates. They were produced by fusion in a silicon carbide furnace up to 1400ºC and then by fast cooling. These materials have been analyzed with techniques of DC conductivity and Impedan
Publicado em: 2000
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7. Caracterização de vidros e vitro-cerâmicas com composição 2Na2O1CaO3SiO2 / Characterization of glasses and glass-ceramics with composition 2Na2O1CaO3SiO2
Glass with composition 2Na2O1CaO3SiO2, undergoes homogeneous crystal nucleation between 450 and 56OoC. The nuclei are essentially spherical and presumable have the same composition as the glass matrix. Measuriments of density, X-ray diffraction, thermal analysis by differential scanning calorimetry (DSC), ultrasonics by pulse-echo method, optical absorption,
Publicado em: 1990