Electrical Properties and Defect Structure of Zirconia: II, Tetragonal Phase and Inversion

Abstract

The defect structure of tetragonal zirconia was investigated by measuring the temperature and oxygen partial pressure dependence of the electrical conductivity and the electronic transference number. Tetragonal zirconia was a mixed electronic and ionic conductor under all conditions studied. The n-type electronic conductivity observed at high temperatures and low oxygen partial pressures was interpreted on the basis of a defect model involving fully ionized oxygen vacancies. The conductivity change associated with the monoclinic ⇒ tetragonal phase transformation was isothermal, but the rate of change was a function of the thermal history and the method of preparation of the sample.