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[en] The present study is aimed to develop porcelain from locally available raw materials. This porcelain was prepared from the mixture of kaolin, quartz, feldspar, and recycled waste glass. In this work, the expensive K-feldspar was substituted by recycled waste glass derived from broken car glass. The effects of recycled waste glass in partial replacement of K-feldspar for porcelain are discussed. Experimental results showed significant effects of recycled waste glass substitution and sintering temperature on physical properties. Furthermore, the microstructure observation indicated that the replacement of K-feldspar by the recycled waste glass indicates the reducing firing temperature 200°C was achieved by 30wt% glass addition. Moreover, experimental investigations showed excellent mechanical (micro-hardness) and insulating properties (dielectric strength) of the prepared porcelain when compared to that of traditional porcelain insulators. The Vickers micro-hardness found an increase with both glass addition and sintering temperature. Dielectric constant (′), dielectric loss tangent (tanδ) and loss factor (″) were measured at different frequencies. The results reveal that glass addition enhances the dielectric properties of the samples fired at 1100°C. Finally, the best results of phase angle were obtained ∼(−89.2°) for this porcelain. These results prove that our prepared insulator is a dielectric capacitor.
[es]
El presente estudio tiene como objetivo obtener porcelana a partir de materias primas disponibles localmente. Esta porcelana se preparó con la mezcla de caolín, cuarzo, feldespato y residuos de vidrio reciclado. En este trabajo, el costoso feldespato potásico se sustituyó por residuos de vidrio reciclado de vidrio roto de automóviles. Se abordan los efectos de los residuos de vidrio reciclado que sustituyen parcialmente al feldespato potásico en la elaboración de la porcelana. Los resultados experimentales mostraron efectos importantes de la sustitución de residuos de vidrio reciclado y la temperatura de sinterización sobre las propiedades físicas. Además, la observación de la microestructura mostró que la sustitución del feldespato potásico por los residuos de vidrio reciclado indica que la reducción de la temperatura de cocción de 200°C se obtuvo con el 30% del peso de adición de vidrio. Aparte de ello, las investigaciones experimentales mostraron excelentes propiedades mecánicas (microdureza) y aislantes (resistencia dieléctrica) de la porcelana preparada en comparación con las de los aislantes de porcelana tradicionales. La microdureza de Vickers encontró un aumento con la adición de vidrio y la temperatura de sinterización. La constante dieléctrica (’), la tangente de pérdida dieléctrica (tan δ) y el factor de pérdida (”) se midieron a diferentes frecuencias. Los resultados revelan que la adición de vidrio mejora las propiedades dieléctricas de las muestras cocidas a 1.100°C. Finalmente, los mejores resultados del ángulo de fase ∼(-89,2°) se obtuvieron de esta porcelana. Estos resultados demuestran que nuestro aislante preparado es un condensador dieléctrico.Journal
Boletin de la Sociedad Espanola de Ceramica y Vidrio (Internet); ISSN 2173-0431; 
; v. 58(1); 10 p
; v. 58(1); 10 p
[en] The adsorption of S on the Si(001)c(4 x 2) surface is studied by first-principles total-energy calculations. We started with the adsorption of a single atom up to a full-monolayer coverage. The first S atom occupies a bridge site, on top of a Si dimer that becomes completely symmetric. At half-monolayer coverage, all bridge sites are occupied, and all Si dimers become symmetric. The overall periodicity is (2 x 1). The adsorption of an additional S atom results in the breaking of two Si dimers. From this point and up to one monolayer, it is energetically more favorable for the S atoms to be adsorbed along the [bar 110] direction. At full monolayer coverage, all Si dimers are broken, and the Si surface is dereconstructed with all Si atoms near bulk ideal positions
Journal
Physical Review. B, Condensed Matter and Materials Physics; ISSN 1098-0121; ; v. 64(7); p. 075317-075317.5
; v. 64(7); p. 075317-075317.5
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