La
1–xSr
xMn
0.8Cu
0.2O
3–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 Sr
2+ content because substituted Sr ions cause an increase in Mn
4+ ions, which has a smaller ionic radius than Mn
3+. 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 Mn
4+ ions, which can enhance the electrical conductivity.
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