Investigation on samarium and yttrium co-doping barium zirconate proton conductors for protonic ceramic fuel cells

Abstract Trivalent rare-earth cation (R 3+ ) and Y 3+ co-doped BaCeO 3 materials show an enhanced proton conductivity than single Y doped BaCeO 3 material. For the same purpose, Sm 3+ and Y 3+ as paired ions are incorporated into BaZrO 3 perovskite structure. The crystal structure, electrical conductivity and sinterability of Sm 3+ and Y 3+ co-doped BaZr 0.8 Y 0.2-x Sm x O 3-δ (BZYS, x = 0, 0.05, 0.1, 0.15, 0.2) materials are investigated for the potential electrolyte application of protonic ceramic fuel cells. Powder XRD diffraction shows BZYS with the cubic perovskite structure and a decrease of lattice constants with increasing Sm 3+ content indicates Sm 3+ doped into perovskite B site. Although the sinterability enhances by Sm 3+ introduction, the grain interior conductivity, specific grain boundary conductivity and total conductivity all cannot be improved. This proves that, unlike BaCeO 3 proton conductors, Sm 3+ and Y 3+ co-doping strategy cannot improve the charge transport properties of BaZrO 3 proton conductors, which is the main contribution of this paper. Through comprehensively considering sinterability and electrical conductivity, the BZYS5 (BaZr 0.8 Y 0.15 Sm 0.05 O 3-δ ) is considered as the potential electrolyte material and the corresponding protonic ceramic fuel cell shows the peak power density of 180 mW cm −2 at 700 °C.