New cathode compositions based on La0.84Sr0.16Mn1−xMxO3, where M = Al, Ga for solid oxide fuel cell

In order to identify new cathode compositions for the high temperature solid oxide fuel cell, we have investigated the effect of the trivalent cations Al and Ga at the Mn site of the well-studied cathode composition La0.84Sr0.16MnO3. All the compositions have been prepared by the low temperature citrate–nitrate auto-ignition process and sintered within the temperature range of 1150–1350 °C for 4 h. In order to understand the compatibility of the prepared samples as alternative cathode materials, we compared their electrical conductivity and thermal expansion coefficient with those of La0.84Sr0.16MnO3 and yttria-stabilized zirconia. A 10 mol% Al doped La0.84Sr0.16MnO3 composition exhibited a conductivity of around 122 S cm−1 at 950 °C and a thermal expansion coefficient of 11.04 × 10−6 K with a minimum reactivity towards yttria-stabilized zirconia. Though the conductivity of the new composition is lower than that of La0.84Sr0.16MnO3 (169 S cm−1 at 950 °C), it is still high enough for use as a cathode material.