UV-visible absorption characteristics of TEOS-derived and Cr-doped silica sonogels aged in different pH solutions and heat treated up to 600 degrees C

dc.contributor.authorDonatti, D. A.
dc.contributor.authorRuiz, AIR
dc.contributor.authorDe Moraes, F. G.
dc.contributor.authorVollet, D. R.
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.date.accessioned2014-05-20T15:22:43Z
dc.date.available2014-05-20T15:22:43Z
dc.date.issued2003-08-01
dc.description.abstractCr-doped xerogels were obtained by sol-gel process from the acid-catalyzed and ultrasound-stimulated hydrolysis of tetraethoxysilane (TEOS) with addition of CrCl3.6H(2)O in water solution during the liquid step of the process. The gels were aged immersed in different pH solutions for about 30 days, after that they were allowed to dry. The samples were annealed at temperatures ranging from 40 to 600degreesC and analyzed by UV-visible absorption spectroscopy. Cr3+ is the preferable oxidation state of the chromium ion in the gels annealed up to 250-300degreesC, in the case of aging in solutions of pH=5 and 11. A high UV absorption below similar to320 nm, due to the host gel, and different absorption bands, depending on the temperature, due to the chromium ion were observed in the xerogels at temperatures below similar to250degreesC, in the case of aging in solutions of pH=1 and 2. These absorption bands have not been assigned. Above 300degreesC up to 600degreesC, Cr5+, and possibly Cr6+, are the preferable oxidation states of the chromium ion independent of the pH of the aging solution, so the xerogels turn to a yellowish appearance in all cases.en
dc.description.affiliationUNESP, Dept Fis, IGCE, BR-13500970 Rio Claro, SP, Brazil
dc.description.affiliationUnespUNESP, Dept Fis, IGCE, BR-13500970 Rio Claro, SP, Brazil
dc.format.extent31-35
dc.identifierhttp://dx.doi.org/10.1023/A:1025676817852
dc.identifier.citationJournal of Sol-gel Science and Technology. Dordrecht: Kluwer Academic Publ, v. 28, n. 1, p. 31-35, 2003.
dc.identifier.doi10.1023/A:1025676817852
dc.identifier.issn0928-0707
dc.identifier.lattes3538107401166553
dc.identifier.lattes5890636096105376
dc.identifier.lattes2661573794233385
dc.identifier.urihttp://hdl.handle.net/11449/33659
dc.identifier.wosWOS:000185229200004
dc.language.isoeng
dc.publisherKluwer Academic Publ
dc.relation.ispartofJournal of Sol-Gel Science and Technology
dc.relation.ispartofjcr1.745
dc.relation.ispartofsjr0,477
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.subjectUV-visible absorptionpt
dc.subjectCr-doped sonogelpt
dc.subjectaging pHpt
dc.subjectheat treatmentpt
dc.titleUV-visible absorption characteristics of TEOS-derived and Cr-doped silica sonogels aged in different pH solutions and heat treated up to 600 degrees Cen
dc.typeArtigo
dcterms.licensehttp://www.springer.com/open+access/authors+rights
dcterms.rightsHolderKluwer Academic Publ
unesp.author.lattes3538107401166553
unesp.author.lattes5890636096105376
unesp.author.lattes2661573794233385
unesp.campusUniversidade Estadual Paulista (Unesp), Instituto de Geociências e Ciências Exatas, Rio Claropt
unesp.departmentFísica - IGCEpt

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