Influence of V₂O₅, Nb₂O₅, Sb₂O₅ and Ta₂O₅ on microstructure and non-ohmic electrical properties of SnO₂-based systems

This work examines the influence of pentoxides (V2O5, Nb2O5, Sb2O5 and Ta2O5) when utilized as dopants on the microstructure, morphology and non-ohmic electrical properties of a SnO2-based ceramic systems. Characterization results show no phase transitions and a microstructure formed by sintered grains with an estimated average size of 5.6-9.4 mu m. Reference and doped samples exhibit nonlinear electrical behaviour except that doped with V2O5. The highest value of the coefficient of nonlinearity alpha is 15.16, and the lowest porosity of 1.84 % for samples doped with Nb2O5. These findings that the Nb+5 ion exhibits a higher proclivity to substitute Sn+4, generating free electrons and defects that create potential barriers and improve grain conductivity. Subtle differences between pentavalent ions in radii and electronegativity are discussed as detrimental factors for their solid solubility in the ceramic matrix.