Effect of Zr substitution for Ce in BaCe0.8Gd0.15Pr0.05O3−δ on the chemical stability in CO2 and water, and electrical conductivity

Abstract

In this paper, for the first time, we report the chemical stability of a highly proton conducting Gd+Pr-codoped BaCe_0.8−xZr_xGd_0.15Pr_0.05O_3−δ (BCZGP) (0.01 < x < 0.3) as a function of Zr-doping in H₂O vapour, 30 ppm H₂S in H₂, and pure CO₂ along with its electrical conductivity in air, N₂ + 3% H₂O, H₂ + 3% H₂O and N₂ + D₂O. All prepared BCZGP compositions retain the original cubic perovskite-type structure in 30 ppm H₂S in H₂ at 600 °C. BCZGP with x = 0.3 shows significant stability under pure CO₂ at 400 °C, while upon exposure to H₂O vapor all compositions form Ba(OH)₂·xH₂O. The maximum electrical conductivity obtained with higher Zr-doping in BCZGP (x = 0.3) is 7.6 × 10⁻³ S cm⁻¹ which is about 30% of that of the parent compound BaCe_0.8Gd_0.15Pr_0.05O_3−δ. Current work clearly shows that Zr-doping at x = 0.3 increases the stability of BCZGP under 30 ppm H₂S and pure CO₂ at intermediate temperatures (T ≤ 400 °C), and retains good proton conductivity in H₂ containing atmosphere.