Simultaneous optimization of Seebeck, electrical and thermal conductivity in free-solidified Bi0.4Sb1.6Te3 alloy via liquid-state manipulation

(BiSb)(2)Te-3-based alloy is one of the best p-type thermoelectric (TE) materials near room temperature. However, it is challenging to improve its ZT value due to the interrelated Seebeck coefficient (S), electrical conductivity (sigma), and thermal conductivity (kappa). In this study, the synergistic optimization of S, sigma, and kappa has been easily achieved in Bi0.4Sb1.6Te3 alloy by liquid-state manipulation (LSM). Specifically, more Te-rich eutectic strips are observed in the LSM sample, which would increase carrier density (p) and thus improve sigma. Meanwhile, via LSM, the raised effective mass m (*) could compensate the effect of increased p on S and thus an enhanced S is obtained. Furthermore, the larger amount of nanoparticles, higher density of lattice distortions, and dislocations in the LSM sample would contribute to scattering phonons and a lower kappa is attained. As a result, the highest ZT of 0.7 at 352 K is attained which is 40% higher than that of traditional melted Bi0.4Sb1.6Te3 alloy.