Enhanced thermoelectric properties of AgSbTe2 by doping for room-middle temperature applications

• Main Author: Toh, Clara Lin Long
• Other Authors: Alex Yan Qingyu
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering
• Online Access: https://hdl.handle.net/10356/176139
• Institution: Nanyang Technological University

AgSbTe2 (AST) has garnered attention for its promising thermoelectric performance characterised by its low thermal conductivity and high Seebeck coefficient, particularly in the medium-temperature range. However, the structure of AgSbTe2 is unstable, leading to the precipitation of secondary phases like Ag2Te and a deterioration in performance. This study explores the application of a high-entropy strategy by doping AgSbTe2 with Sb2Si2Te6, Bi2Si2Te6, CuGaTe2, Ti, Cu, and Si dopants to further enhance the thermoelectric performance of AgSbTe2. The incorporation of dopants inhibits the formation of secondary phases, reduces lattice thermal conductivity, and adjusts carrier concentrations. The characterisation of the samples was carried out using X-ray Diffraction (XRD), and the thermoelectric properties of the samples were measured using ULVAC ZEM-3 and Laser Flash Analysis (LFA). The findings showed that the addition of Cu and Ti dopants suppressed the formation of secondary phases. When doping AST with Cu, a maximum zT of 1.00 at 673K was obtained due to a decreased thermal conductivity and lattice thermal conductivity, and increased power factor. Hence, (AST)0.9Cu0.1 yielded the best thermoelectric performance among all the samples. This report will explore the potential reasons behind these observations.