Synergistic strategy for enhancing the thermoelectric properties of Bi0.5Sb1.5Te3 with excess Te through low-temperature liquid phase sintering method

Abstract

The thermoelectric properties of Bi0.5Sb1.5Te3 synthesized through the low-temperature liquid phase sintering (LPS) method can be significantly improved by employing a synergistic approach. During the heat treatment, excess Te undergoes self-swelling under optimal sintering pressure, facilitating the slip of matrix grains perpendicular to the applied pressure and subsequent recrystallization, leading to enhanced electrical properties. Building upon this basis, the heightened Seebeck coefficient and power factor of the thermoelectric matrix stem from the incorporation of 0.6 vol% B4C nanoparticles. Simultaneously, lattice thermal conductivity experiences notable suppression due to enhanced phonon scattering induced by additional interfaces, defects, and second-phase. Lastly, a markedly improved maximum ZT value of 1.30 at 333 K is achieved when the volume percentage of B4C nanoparticles is 0.6 vol%, representing a remarkable 23% enhancement compared to the untreated sample. These results indicate that the LPS method, coupled with the enhanced second nanophase scattering mechanism, is beneficial to enhancing the thermoelectric properties of Bi2Te3-based materials.