Enhanced thermoelectric performance in n-type Bi2Te2.95Se0.05 bulks fabricated by high pressure sintering technique

Bi2Te2.95Se0.05 bulk materials were prepared by high pressure sintering (HPS) technique under varying pressures. The HPS samples were then annealed for 36 h in vacuum at 633 K. The phase composition, morphology and thermoelectric properties were determined. The results show that high pressure has a significant effect on the structure and thermoelectric properties of the samples. The samples consist of nanoparticles before and after annealing. HPS together with annealing can improve the TE properties of the sample by decreasing the thermal conductivity of the sample with nanostructures. The Bi2Te2.95Se0.05 fabricated under 6.0 GPa at 673 K and subsequently annealed at 633 K for 36 h exhibits good TE properties. The ZT values first increased from 0.9 at 298 K to the maximum value of 1.11 at 373 K, then decreased to 0.91 at 473 K. Such results can be attributed to the good electrical property and small thermal conductivity of the samples. The results can be applied to the field of thermoelectric power generation.