Fabrication and characterization of the p-type (Bi_2Te_3)_x(Sb_2Te_3)_(1-x) thermoelectric crystals prepared via zone melting

摘要

In the present study, p-type (Bi_2Te_3)_x(Sb_2Te_3)_(1-x). crystals with various chemical compositions (x = 0.2, 0.22, 0.235, 0.25, 0.265, 0.28 and 0.3) were fabricated through the zone melting method. Thermoelectric properties, including Seebeck coefficient (alpha), electrical conductivity (sigma), thermal conductivity (kappa) and Hall constants, were measured at room temperature, 300 K. The influence of the variations of Bi_2Te_3 content (x) on the thermoelectric properties was studied. The increase of Bi_2Te_3 content (x) caused a decrease in (carrier) hole concentration and thus a decrease of sigma and an increase of alpha. The maximum figure of merit (Z = alpha~2sigma/kappa) of 2-7 X 10~(-3) K~(-1) was obtained at about 300 K for the composition of 25 percent Bi_2Te_3-75 percent Sb_2Te_3 with 3wt percent excess of Te.