Ceramic electrolytes based on (Ba1 − x Ca x )(Zr0.9Y0.1)O3 solid solution

Abstract

The aim of this work was to study the electrical and electrochemical properties of the (Ba1 − xCax)(Zr0.9Y0.1)O3 solid solutions. The powders of different calcium content (x = 0, 0.05, 0.1, and 1) were prepared by a thermal decomposition of organo-metallic precursors containing ethylenediaminetetraacetate acid. X-ray diffraction analysis showed that a small substitution of calcium for barium caused formation of cubic solid solutions with the decreasing cell parameters. Electrical conductivity measurements were performed by the d.c. four-probe method in controlled gas atmospheres containing Ar, air, H2, and/or H2O at temperature from 300 to 800 °C. It was found that the conductivity depended on a chemical composition of the samples and the atmosphere. Overall, the electrical conductivity was higher in wet atmospheres that contained oxygen that was in accordance with the model of a proton transport in perovskite structure which assumed the presence of the oxygen vacancies. The solid solution containing 5 mol% of calcium showed the highest conductivity and the lowest activation energy of conductivity regardless of the atmospheres; this can be attributed to the local changes in the cubic perovskite structure. Test results for CaZr0.9Y0.1O3 used as an electrolyte in solid oxide galvanic cells involving CaCr2O4 as a reference electrode are also reported.