Combined hot extrusion and spark plasma sintering method for producing highly textured thermoelectric Bi2Te3 alloys

• Published in: Journal of the European Ceramic Society Vol. 40; no. 8; pp. 3042 - 3048
• Main Authors: Lim, Sang-Soon, Jung, Sung-Jin, Kim, Byung Kyu, Kim, Dong-Ik, Lee, Byeong-Hyeon, Won, Sung Ok, Shin, Joonchul, Park, Hyung-Ho, Kim, Seong Keun, Kim, Jin-Sang, Baek, Seung-Hyub
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2020
• Subjects: Bi2Te3 alloys; Hot extrusion (HE); Spark plasma sintering (SPS); Thermoelectrics; Hot extrusion (HE); Thermoelectrics; Spark plasma sintering (SPS); Bi2Te3 alloys
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2020.03.008

Hot extrusion is a promising method for producing high-performance thermoelectric bismuth telluride alloys because of its ability to create textured microstructures. However, hot extrusion is less favourable for scaling-up because of temperature and strain gradients along the radial direction, and only -textured thermoelectric legs can be obtained because of the fibre-like texture. We suggest a way to overcome these disadvantages by implementing an additional spark plasma sintering process on a stack of extrudates. Using this combined process, we demonstrate the fabrication of 12 × 15 × 13 mm3 p-type (Bi0.2Sb0.8)2Te3 samples from extrudates that had originally been 3 mm in diameter. The evolution of sheet-like texture revealed by SEM, XRD, and EBSD allows us to obtain both - and -textured thermoelectric legs from a single specimen that are desirable for low- and high-temperature applications, respectively. Our results demonstrate the combined method as an industry-friendly process for fabricating high-performance thermoelectric materials.