Composition-Dependent Thermoelectric Properties of n-Type Bi^sub 2^Te^sub 2.7^Se^sub 0.3^ Doped with In^sub 4^Se^sub 3

• Published in: Journal of electronic materials 2013-07, Vol.42 (7), p.2178
• Main Authors: Yim, Ju-hyuk, Baek, Seung-hyub, Shin, Hyun-yong, Hyun, Dow Bin, Kim, Jin-sang
• Format: Article
• Language: English
• Subjects: Electric properties; Heat conductivity; Materials science; Nanostructured materials; Research & development expenditures
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-013-2565-4

Issue Title: 2012 International Conference on Thermoelectrics. Guest Editors: Ryoji Funahashi, Donald Morelli, Lasse Rosendahl, and Jihui Yang We present the effects of In^sub 4^Se^sub 3^ addition on thermoelectric properties of n-type Bi^sub 2^Te^sub 2.7^Se^sub 0.3^. In this study, polycrystalline (In^sub 4^Se^sub 3^)^sub x^-(Bi^sub 2^Te^sub 2.7^Se^sub 0.3^)^sub 1-x^ pellets were prepared by mechanical alloying followed by spark plasma sintering (SPS). The thermoelectric properties such as Seebeck coefficient and electrical and thermal conductivities were measured in the temperature range of 300 K to 500 K. Addition of In^sub 4^Se^sub 3^ into Bi^sub 2^Te^sub 2.7^Se^sub 0.3^ resulted in segregation of In^sub 4^Se^sub 3^ phase within Bi^sub 2^Te^sub 2.7^Se^sub 0.3^ matrix. The Seebeck coefficient of the (In^sub 4^Se^sub 3^)^sub x^-(Bi^sub 2^Te^sub 2.7^Se^sub 0.3^)^sub 1-x^ samples exhibited lower values compared with that of pure Bi^sub 2^Te^sub 2.7^Se^sub 0.3^ phase. This reduction of Seebeck coefficient in n-type (In^sub 4^Se^sub 3^)^sub x^-(Bi^sub 2^Te^sub 2.7^Se^sub 0.3^)^sub 1-x^ is attributed to the formation of unwanted p-type phases by interdiffusion through the interface between (In^sub 4^Se^sub 3^)^sub x^ and (Bi^sub 2^Te^sub 2.7^Se^sub 0.3^)^sub 1-x^ as well as consequently formed Te-deficient matrix. However, the decrease in electrical resistivity and thermal conductivity with addition of In^sub 4^Se^sub 3^ leads to an enhanced thermoelectric figure of merit (ZT) at a temperature range over 450 K: a maximum ZT of 1.0 is achieved for the n-type (In^sub 4^Se^sub 3^)^sub 0.03^-(Bi^sub 2^Te^sub 2.7^Se^sub 0.3^)^sub 0.97^ sample at 500 K.[PUBLICATION ABSTRACT]