Improvement in thermoelectric properties by tailoring at In and Te site in In2Te5

We study role of site substitutions at In and Te site in In2Te5 on the thermoelectric behavior. Single crystals with compositions In2(Te1-xSex)5 (x = 0, 0.05, 0.10) and Fe0.05In1.95(Te0.90Se0.10)5 were prepared using modified Bridgman-Stockbarger technique. Electrical and thermal transport properties of these single crystals were measured in the temperature range 6 - 395 K. A substantial decrease in thermal conductivity is observed in Fe substituted samples attributed to the enhanced phonon point-defect scattering. Marked enhancement in Seebeck coefficient S along with a concomitant suppression of electrical resistivity \r{ho} is observed in Se substituted single crystals. An overall enhancement of thermoelectric figure of merit (zT) by a factor of 310 is observed in single crystals of Fe0.05In1.95(Te0.90Se0.10)5 compared to the parent In2Te5 single crystals.