Enhancing Thermoelectric and Mechanical Properties of p-Type (Bi, Sb)₂Te₃ through Rickardite Mineral (Cu_2.9Te₂) Incorporation

Abstract

Bi 2 Te 3 -based alloys are widely utilized in Peltier coolers owing to their highest thermoelectric performance at nearroom-temperatures. However, their peak dimensionless thermoelectric figure of merit, zT, is limited to a narrow temperature window due to minority carrier excitation emerging upon heating at around 400 K. Here, we show how this issue can be overcome by incorporating a synthetic rickardite mineral, Cu 3−x Te 2 , in p-type (Bi, Sb) 2 Te 3 . The significant enhancement of the electronic and thermal properties could be achieved due to small Cu incorporation into the crystal structure of (Bi, Sb) 2 Te 3 and homogeneous precipitation of Cu 3−x Te 2 at the grain boundaries. This leads to a high average zT value (zT ave ) of 1.22 between 350 and 500 K for two compositions, Bi 0.5 Sb 1.5 Te 3 (BST-5) and Bi 0.3 Sb 1.7 Te 3 (BST-3), with peak zT values of 1.32 at 467 K and 1.30 at 400 K, respectively. These high zT values result in a considerably high maximum device ZT of ca. 1.15 and a theoretical efficiency of up to 7% between 325 and 525 K. Additionally, room-temperature micro-hardness is substantially improved, which is desirable for constructing reliable and durable thermoelectric modules.

High‐Efficiency Thermoelectric Module Based on High‐Performance Bi0.42Sb1.58Te3 Materials

“…Recently, many preparation techniques such as high energy ball milling and following by hot pressing (HP), [17,18] spark plasma sintering (SPS), [19][20][21] melt spinning (MS), [22][23][24] and hot deformation (HD) [25][26][27] have been applied to enhance the mechanical strength of Bi 2 Te 3 -based material. [28][29][30][31] Unfortunately, the obtained ZT values by these sintering methods are some lower than expected.…”