Síntese e caracterização de ferrita de cobalto

Abstract

Cobalt ferrite (CoFe2O4) nanostructured powders were synthesized by the combustion reaction method using iron nitrate - Fe (NO3)39H2O, cobalt nitrate - Co (NO3)26H2O and glycine - C2H5O2N. The synthesized nanostructured powders were calcined and, from them, pellets were produced, applying a force equivalent to the weight of 5 tons. The pellets were subsequently sintered at temperatures of 900, 1000, 1100, 1200 and 1300 ° C in ambient atmosphere. The volume of each pellet was measured before and after sintering, aiming to determine their respective densification. All the cobalt ferrite powders, non-synthered and sintered pellets were characterized by X-ray diffraction (XRD), in order to identify their respective crystalline phases and perform a microstructural analysis by the Williamson-Hall method. Thermogravimetric analyzes (TG) were performed for the nanostructured, calcined and non-calcined powder, at heating temperature up to 1200 ° C. The XRD analysis showed that, in the temperature range of 900 to 1300 °C, the increase in the sintering temperature causes a huge reduction in strain, while from 1000 to 1300 °C there is also an increase in the average size of crystallites in the material. The data suggest that a sintering process with two temperature stages (a short high temperature stage followed by a long lower temperature stage) may be suitable for obtaining a more important densification of the samples.