Estudo das propriedades estruturais e dielétricas da matriz cerâmica SrTiO3 com adição de cobalto

• Ano de defesa: 2019
• Autor(a) principal: Siqueira, Filipe Baka Lopes Barros
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Mato Grosso; Brasil; Instituto de Ciências Exatas e da Terra (ICET); UFMT CUC - Cuiabá; Programa de Pós-Graduação em Química
• Palavras-chave em Português: Perovskitas; Método precursores poliméricos; Nanopartículas; Método de Rietveld; Espectroscopia de impedância; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA; Perovskite; Polymeric precursor method; Nanoparticles; Rietveld method; Impedance spectroscopy
• Link de acesso: http://ri.ufmt.br/handle/1/5625

Titanate perovskite oxides, that unit formula is 3, belong to the advanced ceramic materials class and are characterized by having good electro-optical and piezoelectric properties, having applications in the technological areas like sensor electronics, semiconductors, integrated circuits, oscillators, multilayer capacitors, high temperature transducers, and others. Most of the titanate perovskite oxides, strontium titanate (3) has been pointed as a promising candidate for photocatalysis because it’s physical band gap property has a range of 3.1 ~ 3.7 capable of absorbing UV radiation, besides has applications in solar cells and gaseous sensors. In the present work is presented the synthesis of nanostructured titanate perovskite type ceramics, and for the preparation of the ceramic precursor resins, was used the composition of (1−)3, where has values of 0, 0.01, 0.03 and 0.05 mol by the Polymeric Precursor Method. To evaluate the influence of cobalt doping on the structural and dielectric properties of the ceramic matrix, we used experimental X-ray diffraction (XRD) techniques, and impedance spectroscopy. The XRD analysis reveals that the doping altered the ceramic matrix of the material, where the lattice parameters were increased by the influence of cobalt doping. While the results obtained by the Rietveld Method reveal an increase in unit cell volume and decrease in crystallite size, an increase in cobalt concentration in the ceramic matrix. In addition, the concentration of cobalt in the ceramic matrix caused a secondary phase formation of strontium carbonate (3). Regarding the results of the dielectric characterization, it was observed that the real and imaginary impedance dependence as a function of temperature and frequency, where their values decrease as the dopant ion concentration in the matrix is increased. The preparation method of the present work was satisfactory for the preparation of 3 ceramics and its doping.