Thermoelectric Properties of n-type (Bi_2Se_3)_x(Bi_2Te_3)_(1-x) Crystals Prepared by Zone Melting

摘要

In the present study, n-type (Bi_2Se_3)_x(Bi_2Te_3)_(1-x) crystals with various chemical compositions were fabricated by the zone melting method. Thermoelectric properties, including Seebeck coefficient (α), electrical conductivity (σ) and thermal conductivity (k), were measured in the temperature range of 300-500 K. The influence of the variations of Bi_2Te_3 and Bi_2Se_3 content on thermoelectric properties was studied. The increase of Bi_2Se_3 content (x) caused an increase in carrier concentration and thus an increase of a and a decrease of a. The maximum figure of merit (ZT = α~2 σT/k) of 0.87 was obtained at about 325 K for the composition of 93%Bi_2Te_3-7%Bi_2Se_3 with doping TeI_4.