Inhibition grain growth and electrical properties by adding In2O3 to SnO2-Co3O4-Ta2O5 ceramics

Abstract

In this contribution the effect of In₂O₃ additions on the microstructure, physical, and electrical properties of the SnO₂-Co₃O₄-Ta₂O₅ ceramic system was investigated. Since the effect of In₂O₃ has been studied typically at low levels, special attention has been paid to the effect of high levels (1 and 2 mol % In₂O₃) in the ceramics. Results show that up to 0.1 mol % In₂O₃, an increase of indium oxide content is correlated with grain size reduction and an increase of the nonlinearity coefficient (a) and breakdown voltage (E_B), producing an augmentation by a factor of 2 in the nonlinearity coefficient and an increment by a factor of 8 in the breakdown voltage. However, shrinkage () and measured density are not influenced by the addition of indium oxide. For samples with 1 and 2 mol % In₂O_3, in non-calcined condition, In₂O₃ is present with cubic structure. However, in calcined specimens, In₂O₃ is not detected anymore and SnO₂-crystal structure undergoes a change from tetragonal to cubic. These ceramic samples exhibit high resistivity, behaving like dielectric materials.