Co-doping effect on the microstructural and electrical properties of barium stannate materials

Abstract

Proton-conducting perovskite oxides are of considerable interest to researchers as promising electrolytes for low- and intermediate solid oxide electrochemical cells. Therefore, designing new potential proton-conducting phases and improving the functional properties of known materials are of great importance from both fundamental and applied viewpoints. In the present work, BaSnO3 was selected as a reference proton-conducting system and then a co-doping strategy was employed to analyze ‘composition – structure – microstructure – transport properties’ relationships. To perform such an analysis, the properties of previously studied BaSn0.7M0.3O3–δ (M = In, Sc, Y) compounds were compared here to their co-doped derivatives, BaSn0.7In0.15Sc0.15O3–δ, BaSn0.7Y0.15Sc0.15O3–δ, and BaSn0.7In0.15Y0.15O3–δ. It is found that the type of dopant affects the materials sinterability, when more coarse-crystalline ceramics are formed with increasing the average ionic radii at the Sn-position. The introduction of Y3+-cations reduces both ionic and hole conductivities compared to single-doped with In3+ or Sc3+ barium stannate materials. However, simultaneous doping with In3+/Sc3+ cations minimizes the contribution of hole conductivity compared to that of Sc-doped barium stannate with the same acceptor dopant concentration.