Ionic and Electronic Conductivity in Y 2 O 3‐Doped Monoclinic ZrO2

Abstract

The electronic and ionic conductivities of were determined as a function of temperature, oxygen partial pressure, and trivalent dopant content. The experimental observations were in reasonable agreement with the proposed defect structure model. Ionic conductivity for undoped zirconia was attributed to doubly ionized oxygen interstitials at high oxygen pressures and to doubly ionized oxygen vacancies at the lower extreme of the oxygen partial pressure. Doped zirconia, contrary to the undoped sample, showed maximum ionic transport at intermediate oxygen pressures. The ionic conductivity, due to extrinsic dopant effects, increased by increasing the amount of dopant and its range extended over a wider oxygen partial pressure. The observed decrease in activation energy for ionic conductivity upon doping was attributed to the formation of anion vacancies whose concentration is directly proportional to the dopant content. The 1 mole per cent (m/o) sample showed predominant ionic transport.