Crystal structure analysis and thermoelectric properties of p-type pseudo-binary (Al_2Te_3)_x-(Bi_(0.5)Sb_(1.5)Te_3)_(1-x) (x = 0 approx 0.2) alloys prepared by spark plasma sintering

摘要

p-Type pseudo-binary alloys (Al_2Te_3)_x-(Bi_(0.5)Sb_(1.5)Te_3)_(1-x) (x=0 approx 0.2) were prepared by spark plasma sintering (SPS) technique and their thermoelectric properties were evaluated. Measurements show that the Seebeck coefficient decreases and electrical conductivity increases with Al_2Te_3 content increasing due to a possible increment of free carrier (holes) concentration and establishment of special conducting mechanism upon adding Al_Te_3. Thermal conductivity (kappa) increases with temperature but reduces noticeably over the broad temperature range, such a reduction is directly attributed to the enhancement of phonon scattering resulted from both the precipitation of the second phase AlSb and nearly 12 percent atomic occupation of element Al in Tel and Te2 sites in the crystal. The maximum ZT value of 0.86 can be obtained for x=0.1 at 419 KAPPA, which is 0.28 higher than that of Bi_(0.5)Sb_(1.5)Te_3 under the same fabrication technology.