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

Abstract

Titanate perovskite oxides, that unit formula is 𝐴𝑇𝑖𝑂3, 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 (𝑆𝑟𝑇𝑖𝑂3) has been pointed as a promising candidate for photocatalysis because it’s physical band gap property has a range of 3.1 ~ 3.7 𝑒𝑉 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 𝑆𝑟𝐶𝑜𝑥 𝑇𝑖(1−𝑥)𝑂3, where 𝑥 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 (𝑆𝑟𝐶𝑂3). 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 𝑆𝑟𝑇𝑖𝑂3 ceramics and its doping.