Effects of transition metal addition on sintering and electrical conductivity of La-doped CeO₂ as buffer layer for doped LaGaO ₃ electrolyte film

Effects of transition metal additives (0.5 at.% Fe, Mn, and Co) on densification, microstructure, crystal structure, and electrical conductivity of Ce_0.6La_0.4O₂ (LDC) were investigated. The power generation property of a single cell using LDC with the transition metal addition as buffer layer was measured. The addition of Co decreased the sintering temperature of LDC to 1373 K and increased the grain size when the sintering was performed at 1623 K. No impurity phase appeared by the addition of transition metals. The total conductivity of the Co-LDC sample sintered at 1373 K was even higher than that of LDC sintered at 1623 K, and Co-LDC sintered at 1623 K exhibited a conductivity of around 0.01 S cm^{- 1} at 973 K for the high density and large grain size. The single cell using an LSGM electrolyte film and Co-LDC buffer layers showed an open circuit voltage (~ 1.1 V) close to the theoretical value and the maximum power density of 974, 353, and 84 mW cm^{- 2} at 973, 873, and 773 K, respectively. Thus, Co-LDC is a promising buffer layer for enhanced sintering density and decreasing the ohmic resistance in anode supported SOFCs using LSGM electrolyte films.