High temperature thermoelectric properties of Sr and Fe doped SmCoO3 perovskite structure

Sm1−xSrxCo1−yFeyO3 specimens with perovskite structures were prepared by a solid-state reaction to investigate their high temperature thermoelectric properties. The crystal structures of Sm1−xSrxCo1−yFeyO3 polycrystalline samples were investigated by means of an X-ray diffraction method. All specimens showed p-type semiconducting behaviors and their electrical conductivity (σ), Seebeck coefficient (α), thermal conductivity (k) and ZT were measured at high temperatures. Effects of dopant ions on their thermoelectrical properties were also investigated. An acceptor-doping effect and distortion of the perovskite structure exerted an influence on the carrier concentration. Fe3+ ion doped into Co3+ site enhanced the Seebeck coefficient and decreased the electrical conductivity simultaneously. On the contrary Sr2+ ion doped into Sm3+ site enhanced the electrical conductivity and decreased the Seebeck coefficient simultaneously. However heavy-doped cases (>10 mol%) caused a negative effect on the power factor values. The maximum power factor of this system, 2.0410−4 W/mK2 at 786 K was comparable to that of Ca3Co4O9 system.