Effect of nominal Sb₂Te₃content on thermoelectric properties of p-type (Bi₂Te₃)x(Sb₂Te₃)1−xalloys by MA–HP

p-type (Bi 2 Te 3 ) x (Sb 2 Te 3 ) 1− x alloys with homogeneous and fine microstructure were prepared by the mechanical alloying–hot pressing (MA–HP) method in the present work. X-ray diffraction, energy dispersive x-ray spectroscopy, scanning electron microscope–backscattered electron imaging were performed to characterize the MA–HPed materials. The effect of nominal Sb 2 Te 3 content on mechanical and thermoelectric properties of the (Bi 2 Te 3 ) x (Sb 2 Te 3 ) 1− x was investigated. Thermoelectric properties were measured at 300 K. By increasing the nominal molar fraction of Sb 2 Te 3 from 0.7 to 0.9, the carrier concentration ( n c ) increased obviously from 0.43 × 10 19 to 3.08 × 10 19 cm −3 ; however, carrier mobility (μ) fluctuated between 198.0 and 285.5 cm 2 V −1 s −1 , and the Seebeck coefficient (α) and electrical resistivity (ρ) decreased acutely. The thermal conductivity (κ) increased with increase in the nominal Sb 2 Te 3 content, while the lattice thermal conductivity (κ ph ) decreased abruptly from 0.820 to 0.297 W m −1 K −1 . When the nominal molar fraction of Sb 2 Te 3 was 0.8, the resultant maximum power factor (PF) and thermoelectric figure of merit ( Z ) of the p-type (Bi 2 Te 3 ) x (Sb 2 Te 3 ) 1− x alloys reached 3.81 × 10 −3 W m −1 K −2 and 3.23 × 10 −3 K −1 at 300 K, respectively. The bending strength reached 64 MPa, which was 3–5 times larger than that of single crystal materials.