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

Trivalent rare-earth cation (R3+) and Y3+ co-doped BaCeO3 materials show an enhanced proton conductivity than single Y doped BaCeO3 material. For the same purpose, Sm3+ and Y3+ as paired ions are incorporated into BaZrO3 perovskite structure. The crystal structure, electrical conductivity and sinterability of Sm3+ and Y3+ co-doped BaZr0.8Y0.2-xSmxO3-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 Sm3+ content indicates Sm3+ doped into perovskite B site. Although the sinterability enhances by Sm3+ introduction, the grain interior conductivity, specific grain boundary conductivity and total conductivity all cannot be improved. This proves that, unlike BaCeO3 proton conductors, Sm3+ and Y3+ co-doping strategy cannot improve the charge transport properties of BaZrO3 proton conductors, which is the main contribution of this paper. Through comprehensively considering sinterability and electrical conductivity, the BZYS5 (BaZr0.8Y0.15Sm0.05O3-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.