Produção de BI4TI3O12 via rota sol-gel modificada

• Ano de defesa: 2013
• Autor(a) principal: Ferreira, Rudson da Conceição
• Orientador(a): Macedo, Zélia Soares
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Física
• Palavras-chave em Português: Produção de cerâmicas; Tecnologia química; Polimerização; Bismuto; Titanato de bismuto; Sol-gel; Polivinil álcool
• Palavras-chave em Inglês: Ceramic industries; Chemical technology; Polymerization
• Área do conhecimento CNPq: CNPQ::CIENCIAS EXATAS E DA TERRA::FISICA
• Link de acesso: https://ri.ufs.br/handle/riufs/5308

The main goal of this study was to develop a methodology for the production of Bismuth Titanate ceramics in the phase Bi4Ti3O12, based on sol-gel route and using polyvinyl alcohol (PVA) as polymerizing agent. Bi4Ti3O12 is a ferroelectric material with great technological appeal due to its potential application in capacitors and memory devices. Moreover, the sol-gel route with PVA, besides enabling particle size control and low contamination during the synthesis, has the advantage of using less expensive reagents than those used in conventional route. The results indicated that ceramic bodies with single phase and relative density of 70% can be obtained after calcination at 800º C and sintering at 1000º C for 2h. These ceramic bodies had microstructure with sub-micrometric rounded grains that assume platelet morphology when reach micrometric dimensions. The impedance diagram of sintered ceramics presented two characteristic semicircles, thermally activated conductivity and dielectric permittivity characterized by a dispersion at low frequencies due to charge carriers movement in the material. The activation energy for the conductive processes was determined by the low frequency dependence of electric conductivity and modulus on the temperature. In both cases, it was observed an Arrhenius-type behavior with energies around 0.7 eV. Similar values were obtained for the conductive processes in intra-grain region, at high frequencies. In this case, the energies were obtained only by analyzing the electrical module. The results obtained point out to the success of the technique to obtain material with good crystallographic quality through a route that is simplified and cost reduced. In the specific case of the material being studied in this work, additional efforts will be required to achieve ceramics with relative density higher than 90%.