Three dimensional representations of partial ionic and electronic conductivity based on defect structure analysis of BaZr0.85Y0.15O3−δ

The defect structure of BaZr0.85Y0.15O3−δ was systematically analyzed as functions of oxygen and water vapor activity at the temperature where the grain boundary resistance becomes negligible for defect-chemical analyses. AC impedance spectroscopy was used to differentiate the grain and grain boundary contribution on total electrical conductivity. A thermo-gravimetric analysis was employed to estimate the equilibrium constant of hydration reaction as well as the concentrations of ionic charge carriers, protons and oxygen vacancies. Total electrical conductivity was measured by a DC 4-probe method at 800 °C over a range of aO2 from 10− 25 to 1 and aH2O from 10− 4.5 to 10− 1.6 and was analyzed via a non-linear simultaneous fitting method based on previously obtained proton and oxygen vacancy concentrations, to represent the corresponding partial ionic and electronic conductivities in the form of f(aO2,aH2O) within a three dimensional space. Transference numbers of each mobile charge carrier are also presented into the three-dimensional form.