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dc.contributor.authorDonatti, D. A.-
dc.contributor.authorRuiz, A. I.-
dc.contributor.authorVollet, D. R.-
dc.contributor.authorMaceti, H.-
dc.identifier.citationJournal of Non-crystalline Solids. Amsterdam: Elsevier B.V., v. 352, n. 2, p. 167-173, 2006.-
dc.description.abstractSilica xerogels were prepared from sonohydrolysis of tetraethoxysilane and exchange of the liquid phase of the wet gel by acetone. Monolithic xerogels were obtained by slow evaporation of acetone. The structural characteristics of the xerogels were studied as a function of temperature up to 1100 degrees C by means of bulk and skeletal density measurements, linear shrinkage measurements and thermal analyses (DTA, TG and DL). The results were correlated with the evolution in the UV-Vis absorption. Particularly, the initial pore structure of the dried acetone-exchanged xerogel was studied by small-angle X-ray scattering and nitrogen adsorption. The acetone-exchanged xerogels exhibit greater porosity in the mesopore region presenting greater mean pore size (similar to 4 nm) when compared to non-exchanged xerogels. The porosity of the xerogels is practically stable in the temperature range between 200 degrees C and 800 degrees C. Evolution in the structure of the solid particles (silica network) is the predominant process upon heating up to about 400 degrees C and pore elimination is the predominant process above 900 degrees C. At 1000 degrees C the xerogels are still monolithic and retain about 5 vol.% pores. The xerogels exhibited foaming phenomenon after hold for 10 h at 1100 degrees C. This temperature is even higher than that found for foaming of non-exchanged xerogels. (c) 2005 Elsevier B.V. All rights reserved.en
dc.publisherElsevier B.V.-
dc.sourceWeb of Science-
dc.subjectsol-gets (xerogels)pt
dc.titleStructural evolution up to 1100 degrees C of xerogels prepared from TEOS sonohydrolysis and liquid phase exchanged by acetoneen
dc.contributor.institutionUniversidade Estadual Paulista (UNESP)-
dc.contributor.institutionCtr Univ Herminio Ometto-
dc.description.affiliationUNESP, IGCE, Dept Fis, BR-13500970 Rio Claro, SP, Brazil-
dc.description.affiliationCtr Univ Herminio Ometto, BR-13607339 Araras, SP, Brazil-
dc.description.affiliationUnespUNESP, IGCE, Dept Fis, BR-13500970 Rio Claro, SP, Brazil-
dc.rights.accessRightsAcesso restrito-
dc.relation.ispartofJournal of Non-Crystalline Solids-
Appears in Collections:Artigos, TCCs, Teses e Dissertações da Unesp

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