Enhancement of thermoelectric performance of In doped Bi₂Te_2.7Se_0.3 compounds

Bulk samples of (Bi_1-xIn_x)₂ Te _2.7 Se_0.3 (x = 0.00, 0.02, 0.04) were prepared by solid state reaction technique. Powder X-ray diffraction pattern confirms that the polycrystalline samples have hexagonal structure with spacegroup R3‾m. Surface morphology shows a reduction in porous behaviour of the material due to co-doping. Energy dispersive X ray analysis demonstrates the elements present in the sample. Electrical resistivity has shown a quasi-degenerate semiconducting behaviour. Hall effect and Seebeck coefficient confirmed that all the samples are n-type. There is a decrease in thermal conductivity with the variation in dopant concentration. The maximum ZT was found to be 0.6 at 350 K for the sample (Bi_0.98In_0.02)₂ Te _2.7 Se_0.3 which is about 5 times that of the pristine sample Bi₂Te_3.