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Sr 12x Ce x MnO 3 (SCM, 0?1#x#0?4) powders were synthesised by an ethylenediaminetetraacetic acid citrate complexing process, and their properties were investigated. The synthesised Sr 12x Ce x MnO 3 powders showed a pure perovskite phase, whereas the composition with x50?4 had second phases. The unit cell volumes increased with increasing Ce content because substituted Ce ions formed some Mn 3z ions, which have a larger ionic radius than Mn 4z . The electrical conductivity improved with increasing Ce content up to x50?3 (291 S cm 21 at 750uC), revealing a double exchange interaction. Although the electrical conductivity was increased by doping Ce ions, the polarisation resistance increased due to the increase in lattice distortion with doping Ce content. The substitution of Ce ions for Sr in SrMnO 3 led to the formation of larger Mn 3z ions than Mn 4z ions and lattice distortion, which would affect the electrical and oxygen ion conductivity.

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