Publication Date:
2015-12-19
Description:
The electronic structure and thermoelectric properties of MTl 9 Te 6 (M = Bi, Sb) were studied using density functional theory and the semiclassical Boltzmann theory. It is found that the band gaps of BiTl 9 Te 6 and SbTl 9 Te 6 are equal to 0.59 eV and 0.72 eV, respectively. The relative large band gap and strong coupling between Sb s and Te p are helpful to the thermoelectric properties of SbTl 9 Te 6 . Near the bottom of the conduction bands, the number of band valleys of SbTl 9 Te 6 is four and is larger than that of BiTl 9 Te 6 (two band valleys), which will increase its Seebeck coefficient. Although BiTl 9 Te 6 has a larger electrical conductivity relative to relaxation time ( σ / τ ) along the z-direction than that of SbTl 9 Te 6 , the results show that the transport properties of SbTl 9 Te 6 are better than those of BiTl 9 Te 6 possibly due to its large Seebeck coefficient. The maximum value of power factor relative to relaxation time (S 2 σ / τ ) for SbTl 9 Te 6 reaches 4.30 × 10 11 W/K 2 m s at 900 K, that is, originated from its relatively large Seebeck coefficient, suggesting its promising thermoelectric performance at high temperature.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
