Enhancement of thermoelectric properties in Sn doped (In0.95Lu0.05)2O3

In this work, thermoelectric properties in Sn and Lu co-doped In2O3 were investigated. The materials of (In0.95−xLu0.05Snx)2O3 (x = 0, 0.001, 0.01 and 0.04) were synthesized by using a co-precipitation method followed by spark plasma sintering (SPS) process. Sn(+IV) was strategically selected to substitute In(+III) for increasing the electrical conductivity of 5% Lu doped In2O3 [(In0.95Lu0.05)2O3] while remaining the low thermal conductivity of the compound. It was found that the carrier concentration could be increased from 2.1 × 1017 cm−3 to 3.7 × 1020 cm−3 by doping 1% Sn into (In0.95Lu0.05)2O3. As a result, 1% Sn increased power factor with the value of ∼5 × 10−4 W m−1 K−2 at 973 K, which was 5 times higher than that of (In0.95Lu0.05)2O3. It is interesting to note that the band gap energies were widened in the samples doped with 0.1% Sn and 1% Sn due to the Burstein-Moss (BM) shift. Sn doping decreased the thermal conductivity of (In0.95Lu0.05)2O3. Among the as-prepared samples, 0.1% Sn doped (In0.95Lu0.05)2O3 possessed the highest ZT of ∼0.15 at 973 K, which was almost 3 times higher than that of (In0.95Lu0.05)2O3.