The Effect of Space Charge on Blocking Grain Boundary Resistance in Yttrium Doped Barium Zirconate Electrolyte for Solid Oxide Fuel Cells

The higher grain boundary resistance in the proton conducting yttrium doped barium zirconate is one of the major issues to be solved. A new strategy has been experimentally studied on the basis of space charge theory to understand the grain boundary resistance in pristine and 20 mol% yttrium doped barium zirconate by varying the sintering temperature (1200, 1300, 1400 and 1500°C). The electrical response upon applying DC bias indicates the existence of space charge in the grain boundary region of barium zirconate. The Mott Schottky analysis was performed at a lower temperature of 100℃ to infer the information from the grain boundary region. A parabolic reduction in normalized proton concentration was observed from the grain boundary to its core. The barrier height varied in the range of 0.55 – 0.15 V depending on sintering temperature. The increase in dopant concentration along the grain boundary resulted in the reduction of barrier height as well as space charge width. Hence, the presence of yttrium and ...