THE OXYGEN CONDUCTIVITY AND CHEMICAL DIFFUSION IN YBA2CU3O6+X

The ionic conductivity of oxygen was studied in the dense ceramic YBa2 Cu3O6+x using oxygen permeation measurements. The temperature interval of the measurements was 600-850-degrees-C and the limits of the parti al pressure of oxygen were 0.06-1.00 atm. The method was based on the direct determination of the steady flow of oxygen through the specimen in the conditions of constant temperature with a small gradient of ox ygen chemical potential along the sample. The oxygen diffusion coeffic ient was calculated. The activation energy (U) of the oxygen conductiv ity (diffusion coefficient) was determined in the interval 0.35 < x < 0.6. The dependence of the activation energy on the oxygen content in the tetragonal phase U = 2.80 - 1.45x eV was found. This dependence wa s explained by the interaction of the mobile oxygen ions.