Influence of dopant levels on the hydration properties of SZCY and BZCY proton conducting ceramics for hydrogen production
Kwati Leonard, Young-Sung Lee, Yuji Okuyama, Kuninori Miyazaki, Hiroshige Matsumoto
Dense yttrium doped solid solutions of alkaline earth cerate and zirconate with the formula A(Zr5/9Ce4/9)1−xYxO3−δ, (A = Sr and Ba, x = 0.1, 0.2) have been prepared and studied as potential proton conducting electrolytes. Thermo-gravimetric analysis was used to determine the proton concentration in the specimens. BZCY(54)8/92 showed a maximum proton concentration limit of 17.1 mol % compared to only 6.03 mol % for SZCY(54)8/92 and retained the highest proton conductivity of 1.44 × 10−2 S cm−1 in wet 1% H2 at 600 °C. Sufficient chemical stability under 80% steam for 200 h was confirm for the said composition. Approximately similar proton mobility levels were observed at 600 °C for the compositions. The major difference in total conductivity originates mostly from the differences in proton concentration levels. The bulk and grain boundary contributions on the conductivity were strongly dependent on the A-site host, with the grain boundary response being the main source of resistance in the BZCY specimens relative to the SZCY.