The effect of Sb and Nb on the electrical conductivity of tin dioxide based ceramics

The electrical conductivity of Mn doped SnO₂ systems prepared by an organic route (Pechini’s method) has been investigated as a function of antimony and niobium concentration. The conductivity increases with the increase of both concentration ions, however, in a different manner. While the conductivity of niobium doped ceramics increases with the power of 1.6 for the entire range of concentrations studied (0.01–0.7 mol%), the conductivity of antimony doped ceramics increases with the power of 1.9 in the range 0.01–0.05 mol% of Sb; 3.7 in the range 0.05–0.30 mol% and 1.8 in the range 0.30–0.70 mol%. This behavior is attributed to the existence of two stable oxidation states for antimony: Sb³⁺ and Sb⁵⁺, while for niobium there is only one: Nb⁵⁺. The power of 3.7 for Sb would be related to the segregation of this ion on the grain boundary accompanied by an additional contribution coming from the substitution of Sn²⁺ by Sb³⁺ on the grain surface.