ELECTRONIC CONDUCTIVITY IN IN2O3 SOLID-SOLUTIONS WITH ZRO2

The electrical conductivity of In2O3-ZrO2 as well as In2O3 solid solut ions doped with SnO2, CeO2, Nb2O5, Pr6O11, and MgO is investigated, in the temperature range between room temperature and 1300-degrees-C, an d in the oxygen partial pressure range between 5 x 10(-5) and 1 atm. I n2O3 doped with ZrO2 is an electronic conductor, while ZrO2 doped with In2O3 is an oxygen-ionic conductor. The two-phase material of the cub ic (fcc) ZrO2 + cubic (bcc) In2O3 solid solutions is a 3-dimensional c omposite of ionic and electronic conductors. The single-phase In2O3 do ped with ZrO2 is an electronic conductor with a conductivity up to 7 x 10(4) Sm-1 in air. Two maxima in electrical conductivity are found, o ne in the two-phase region and one in the In2O3 single-phase region. L attice defects responsible for electronic conduction in pure and doped In2O3 are discussed. The defect models for In2O3 doped with ZrO2 are proposed, and the Kroger-Vink diagram is constructed. The metastable s olubility of dopants in In2O3 due to the slow phase separation kinetic s influences the electronic conductivity. ZrO2 is a most effective don or for increasing electronic conductivity of In2O3, among hypervalent metal oxides including SnO2, Nb2O5, and CeO2.