Thermoelectric Performance of -Type (Bi85Sb15)1- Sn Materials Prepared by a Pressureless Sintering Technique

In this study, a series of Sn-doped (Bi85Sb15)(1-) Sn ( = 0, 0.025, 0.05, 0.1, 0.2, 0.3) thermoelectric materials was fabricated through mechanical alloying followed by pressureless sintering. The crystal structure was characterized by x-ray diffraction. The electrical transport properties and thermal properties were measured in the temperature range from 77 K to 300 K. The electrical transport as a function of temperature appeared to be characteristic of a semimetal. The Seebeck coefficient gradually changed from negative to positive with increasing Sn doping, showing -type electrical transport properties. It is found that the Seebeck coefficients of the -type Bi-Sb alloys decrease with increasing dopant concentration of Sn, which may be due to increasing carrier concentration. Among the -type alloys, the power factor of (Bi85Sb15)(0.975)Sn-0.025 reached a maximum value of 1.3 x 10(-3) W/mK(2) at 265 K, and the optimum figure of merit value of 0.13 was obtained at 240 K. The results indicate that good -type Bi-Sb alloys can be prepared by this synthesis procedure.