Substitution effect of tetravalent and pentavalent elements on thermoelectric properties in In₂O₃-SnO₂ system

Abstract

Thermoelectric properties of In_2-xM_xO₃ system doped with tetravalent metal (M) ions (Si⁴⁺, Ti⁴⁺, Ge⁴⁺, Sn⁴⁺, Te⁴⁺, and Ce⁴⁺) were investigated at temperatures up to 1273 K. For the Ge-substituted system, the power factor P takes a maximum of 9.5 × 10^-4 W/K²m around 1150 K and dimensionless thermoelectric figure of merit ZT shows a maximum of 0.18 at 1000 K for the x=0.025 sample, which is the solubility limit of Ge. The maximum ZT of the In_1.9M_0.1O₃ series was about 0.13 around 1000 K for the Si⁴⁺, Ge⁴⁺ and Sn⁴⁺ doped samples. We also investigated the thermoelectric properties of the In₂O₃-SnO₂ system doped with pentavalent Sb element to replace the expensive In₂O₃ to the plentiful SnO₂. The Sb atom was preferentially substituted for the In-site and the thermoelectric properties do not exceed those of pure In₂O₃. The potential of the thermoelectric properties in the doped In₂O₃-SnO₂ system was discussed.