n-Type oxide thermoelectric materials remain challenging for various applications because of their average electrical conductivity, high thermal conductivity, and hence low thermoelectric performance. In this work, we have studied the chemical, structural, and transport properties of vanadium doped In 2 O 3 thermoelectric materials prepared via spark plasma sintering (SPS). The solubility of V in In 2 O 3 is about 6 at % and V 4 O 9 as a secondary phase was observed in 8 at %. V doping leads to a synergistic improvement in electrical conductivity with a simultaneous reduction of the thermal conductivity, yielding ZT = 0.42 at 973 K in In 1.88 V 0.12 O 3 that is 320% improvement than that of pristine In 2 O 3 . This enhancement in electrical conductivity is because of change in charge concentration via pentavalent vanadium doping at the trivalent indium site. The scattering of heat-carrying phonons due to the effects of mass fluctuations and substitutional defects caused by V doping leads to a reduction in heat conduction. Our results suggest that the TE properties of In 2 O 3 can be improved by simultaneously increasing PF and reducing thermal conductivity via V doping.

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We report remarkably the enhanced thermoelectric performance of Sn-Zn co-doped In2O3 that were synthesized by a solid-state reaction followed by spark plasma sintering in the mid-temperature range. The X-ray diffraction study indicates that Sn and Zn were successfully co-substituted at the In site without forming any additional phase even at 8% doping concentration. The co-substitution shows a significant increase in the electrical conductivity by band structure modification resulting in a significantly enhanced power factor. The point defect engineering combined with nanostructuring using a high energy ball milling suppressed the lattice thermal conductivity, which eventually resulted in an increased ZT value of 0.32 at 973 K, that is, about 7 times higher than that of pure In2O3. Thus, this study demonstrates the important role of co-substitution in improving the thermoelectric properties of n-type oxides.

The present study reports an enhancement of thermoelectric performance in Au ion implanted V2O5 thin films.