Structural analysis and electrical conductivity of La1−xSrxMn0.8Cu0.2O3−δ (0.1 ≤ x ≤ 0.4) for IT-SOFCs

La1–xSrxMn0.8Cu0.2O3–δ (LSMCu, 0.1 ≤ x ≤ 0.4) powders were prepared using the EDTA-citrate complexing process. The synthesized LSMCu powders were a pure perovskite phase, whereas the composition with x = 0.4 has second phases. The unit cell volumes decreased with increasing Sr2+ content because substituted Sr ions cause an increase in Mn4+ ions, which has a smaller ionic radius than Mn3+. The electrical conductivity also improved with increasing Sr addition in 0.1 ≤ x ≤ 0.3, revealing a small polaron hopping mechanism. The oxidation state of Mn ions increased with the addition of Sr ions in 0.1 ≤ x ≤ 0.3 but the oxidation state of Cu ions was unchanged in 0.1 ≤ x ≤ 0.3. The addition of Sr ions in the A-site of LSMCu can lead to a contraction of the lattice volume because of the decreased Mn–O bond length and increased Mn4+ ions, which can enhance the electrical conductivity.