Electrical conductivity of polycrystalline tin dioxide and its solid solution with ZnO

Abstract

Electrical conductivity (σ) of “pure” and ZnO doped SnO₂ has been measured at different temperatures and oxygen partial pressures ($p_{{\text{O}}_{\text{2}} }$)- From the variation of electrical conductivity of these materials three partial pressure ranges have been identifieD. In the high partial pressure rangeσ increases with decreasing$p_{{\text{O}}_{\text{2}} }$ followed by a$p_{{\text{O}}_{\text{2}} }$ independent region at lower$p_{{\text{O}}_{\text{2}} }$ ´s and finally increases once again with a further decrease of$p_{{\text{O}}_{\text{2}} }$. These variations have been explained on the basis of an anti-Frenkel type defect structure and an interstitial solid solution of ZnO in SnO₂. The activation energy for the conduction process has been estimated and the values are found to differ in two different temperature ranges. In the low temperature range the conductivity is attributed mainly to the chemisorption of oxygen on the surface of the specimen.