Influence of the Sintering Additive (Fe2O3) to the Morphological and Microstructural Development of SnO2 Ceramic Powders

Abstract

The properties of a large number of materials are conditioned by their microstructure. A simple variation in temperature, the treatment time or the presences of impurities have an influence on them. A systematic study was carried out by adding Fe₂O₃ at content levels of 1 to 2 %, enabling its effect on the micro-structural development of the SnO₂ powder to be observed. The effectiveness of the additive to attain a high density is studied in terms of grain growth. Its surface distribution changes the chemical composition of the latter, decreases the surface energy, increases the specific surface area and diminishes porosity. According to the morphology study carried out by SEM Fractograph and in accordance with the fracture pictures found, it appears that certain pores which stay trapped in the grains do not make the attainment of high densities possible. In present case, iron oxide seems to play quite a low role and belongs to the group D classification, since the sizes of the crystallite calculated by the Debye relation offer values of D > 18 nm. To reach densities which are slightly higher, it is necessary to use more rapid thermal treatment.