Conductivity of BaPrO3 based perovskite oxides

To develop higher protonic conductivity, we have been studying a new perovskite-type oxide and found that BaPrO3 based perovskite oxides showed high conductivity in a moist H2 atmosphere. Their conductivity was about 0.1 S/cm at a temperature of 500°C and remained almost constant up to 700°C, which is much higher than that of Ba(Ce0.8Gd0.2)O3−α. Ba(Pr1−xGdx)O3−α prepared by solid state reaction exhibited an orthorhombic and/or cubic perovskite structure and with a high Gd content was stable in a reducing atmosphere. When Ba(Pr0.7Gd0.3)O3−α was used as an electrolyte, the open circuit voltage of the cell was about 1 V and this cell was able to operate at 500°C. During the testing of the cell, the formation of water on an air electrode led us to conclude that mobility of protons in the electrolyte occurred. The dominant conduction species in Ba(Pr1−xGdx)O3−α electrolyte were considered as oxygen ions and/or protons.