High-temperature thermoelectric properties of Sm3+-doped Ca3Co4O9+δ fabricated by spark plasma sintering

Abstract Ca 3- x Sm x Co 4 O 9+ δ (0 ≤ x ≤ 0.3) samples were fabricated by the sol-gel method followed by spark plasma sintering in vacuum. The high-temperature thermoelectric properties of the Ca 3- x Sm x Co 4 O 9+ δ were also studied, with an emphasis placed on the partial substitution of Sm 3+ for Ca 2+ . The sintered Ca 3- x Sm x Co 4 O 9+ δ formed a monoclinic Ca 3 Co 4 O 9 phase and exhibited fine lamellar grains and dense morphology. With increased Sm 3+ content, the electrical and thermal conductivities decreased, whereas the Seebeck coefficient significantly increased. Of the prepared samples, Ca 2.7 Sm 0.3 Co 4 O 9+ δ had the largest dimensionless figure-of-merit (0.175) at 800 °C. The results showed that the partial substitution of Sm 3+ for Ca 2+ in Ca 3 Co 4 O 9+ δ is effective for enhancing its thermoelectric properties.