Thermoelectric (Bi,Sb)2Te3–Ge0.5Mn0.5Te composites with excellent mechanical properties

Abstract

(Bi,Sb)₂Te₃ alloys have been widely used in thermoelectric cooling, but their poor mechanical properties limit the module size to reach higher cooling density. Here, we report the thermoelectric and mechanical properties of (Bi,Sb)₂Te₃–Ge_0.5Mn_0.5Te composites; Ge_0.5Mn_0.5Te has recently been reported to be a promising thermoelectric material with high hardness in a moderate temperature range. Alloying with Ge_0.5Mn_0.5Te not only reduces the lattice thermal conductivity, but also improves the mechanical properties. Along with carrier concentration regulation, both excellent thermoelectric and mechanical properties have been achieved in (Bi,Sb)₂Te₃–Ge_0.5Mn_0.5Te composites. The Vickers hardness increased from 0.45 Gpa for the pristine (Bi,Sb)₂Te₃ to 0.81 Gpa for the sample with 1.0% Ge_0.5Mn_0.5Te, and a Young's modulus of 37.06 Gpa was obtained for the one with 1% Ge_0.5Mn_0.5Te. By adjusting the carrier concentration, the final ZT value of (Bi,Sb)₂Te₃ > 1.1 at 350 K.