Chemically stable Dy–Y double substituted barium zirconate with high proton conductivity and improved sinterability

•BaZr(0.8−x)DyxY0.2O3−δ (0⩽x⩽0.2) powders were synthesized by a wet chemical route.•The ability of the synthesized powders in uptaking water was determined.•Chemical stability of the synthesized powders was evaluated under in wet and CO2 atmosphere.•The conductivity of the sintered pellets was measured by AC impedance spectroscopy.•It was shown that Dy-doped BZY20 ceramic has excellent proton conductivity.•It was proved that Dy-doped BZY20 ceramic has good chemical stability.•It was concluded that Dy-doped BZY20 electrolyte can be considered as a promising electrolyte for solid oxide fuel cell applications. Novel proton conductors BaZr(0.8−x)DyxY0.2O3−δ (BZ0.8−xDxY20, 0⩽x⩽0.2) with high proton conductivity, chemical stability and improved sinterability are developed by partially substituting the Zr site of the 20mol% Y-doped barium zirconate (BZY20) with Dy. A modified Pechini method was applied to synthesize the BZ0.8−xDxY20 powders. The X-ray diffraction patterns of the well-calcined powders indicated that the specimens with 0⩽x⩽0.2 possessed a single-phase of cubic perovskite-type oxides. Stability tests under both CO2 and moist air atmospheres demonstrated that the excellent chemical stability of the base BZY20 material was not influenced by the introduction of Dy. High density pellets with larger grain sizes were obtained at temperatures lower than those commonly employed for the base Y-doped barium zirconate compound. The proton conductivities, measured in different oxidizing and reducing, dry and humidified atmospheres by impedance spectroscopy, were significantly influenced by the Dy amount. In overall, BaZr(0.8−x)DyxY0.2O3−δ solid solutions having Dy∼5–10% showed excellent chemical stability and high conductivity (above 10−2Scm−1 at 600°C, PH2O=0.023), which was influenced by the moisture content of the applied atmosphere.