Park, Gwang Min Lee, Seunghyeok Kang, Jun-Yun Baek, Seung-Hyub Kim, Heesuk Kim, Jin-Sang Kim, Seong Keun 2024-02-13T05:00:38Z 2024-02-13T05:00:38Z 2024-02-13 2023-12 2226-4108 https://pubs.kist.re.kr/handle/201004/148607 This study investigated the effects of KCl treatment on microstructure and thermoelectric properties of n-type Bi2Te2.7Se0.3 (BTS) thermoelectric materials. The innovative KCl treatment was originally intended to introduce nanopores through selective dissolution of KCl from a mixture of thermoelectric materials and KCl. However, it unexpectedly induced substantial variations in material composition and microstructure during the subsequent spark plasma sintering (SPS) process. Hydroxyl groups adsorbed on the powder surface during the dissolution resulted in the emergence of a Bi2TeO5 secondary phase within the BTS matrix after the SPS process at 450 degrees C. The concentration of Bi2TeO5 increased with an increase in the KCl content. Furthermore, a remarkable grain growth occurred at low KCl concentrations, likely due to the liquid-phase formation in a Te-rich composition during SPS. However, excessive Bi2TeO5 at higher KCl concentrations hindered grain growth. These variations in the microstructure had complex effects on electrical properties: The T-eBi antisite defects increased the electron concentration, and Bi2TeO5 reduced electron mobility. Additionally, the lattice thermal conductivity decreased due to the presence of Bi2TeO5, from 0.8 W center dot m(-1)center dot K-1 at 298 K for the pristine BTS to 0.6 W center dot m(-1)center dot K-1 at 298 K for BTS treated with 1 wt% KCl. These insights allowed precise adjustments of the electrical and thermal conductivities, leading to an enhancement in the maximum value of figure-of-merit (ZT) from 0.76 to 0.96 through the selective dissolution of KCl approach. We believe that our observations potentially enable advances in thermoelectric materials by engineering microstructures. English Springer Science + Business Media Understanding secondary phase inclusion and composition variations in the microstructure design of n-type Bi2Te3 alloys via selective dissolution of KCl Article 10.26599/JAC.2023.9220825 1 Journal of Advanced Ceramics, v.12, no.12, pp.2360 - 2370 Journal of Advanced Ceramics 12 12 2360 2370 Y scie scopus 001150314300010 Materials Science, Ceramics Materials Science Article HIGH-THERMOELECTRIC PERFORMANCE NANOSTRUCTURED THERMOELECTRICS TRANSPORT-PROPERTIES BISMUTH TELLURIDE CU ADDITION STABILITY FIGURE MERIT thermoelectric materials Bi2Te3 Bi2TeO5 grain growth n-type KCl