Equilibrium dependence of the conductivity of pure and tin-doped indium oxide on oxygen partial pressure and formation of an intrinsic defect cluster

The dependence of the electrical conductivity of pure (99.999%) and tin-doped indium oxide (In2O3) ceramics on oxygen partial pressure (p(O2)) was investigated at 800 degrees and 850 degrees C. The doping amount of tin was 100-1000 ppm, which is within the solubility limit at the temperatures measured. The conductivity of doped ceramics was independent of p(O2), and the carrier concentration was almost the same as the estimated value from the tin content. The conductivity of the pure In2O3 ceramic was proportional to (p(O2))(-1/10). By considering a singly charged defect cluster of interstitial indium and interstitial oxygen, ((IniOi)-O-center dot center dot center dot '')(center dot), the conductivity dependence is deduced to be proportional to (p(O2))(-1/8). There are large and three adjacent vacant sites, 8a and 16c, in the In2O3 structure to enter indium and oxygen.