Study on the Fabrication and Characterization of LAST and LASTT Based Thermoelectric Generators
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1044-U10-08
Study on the Fabrication and Characterization of LAST and LASTT Based Thermoelectric Generators Chun-I Wu1, Edward J. Timm2, Fei Ren3, Bradley D. Hall3, Jennifer Ni3, Adam Downey1, Jonathan D’Angelo1, Jarrod Short1, Harold Schock2, Eldon Case3, Joe Sootsman4, Mi-Kyoung Han4, Mercouri Kanatzidis4, Duck-young Chung5, and Timothy P. Hogan1 1 Electrical and Computer Engineering, Michigan State University, 2120 Engineering Building, East Lansing, MI, 48824 2 Mechanical Engineering, Michigan State University, East Lansing, MI, 48824 3 Chemical Engineering and Material Science, Michigan State University, East Lansing, MI, 48824 4 Chemistry, Northwestern University, Evanston, IL, 60208 5 Materials Science Division, Argonne National Laboratory, Argonne, IL, 60439 ABSTRACT Thermoelectric modules are of great interest for power generation applications where temperature gradients of approximately 500K exist, and hot side temperatures near 800K. The fabrication of such modules requires optimization of the material compositions, low contact resistivities, and low thermal loss. AgPbmSbTe2+m (LAST) and Ag(Pb1-xSnx)m SbTe2+m (LASTT) compounds are among the best known materials appropriate for this temperature range. Various measurement systems have been developed and used to characterize bulk samples in the LAST and LASTT systems within this operating temperature range. From the characterized data, modeling of modules based on these materials and segmented legs using LAST(T) with Bi2Te3 have been used to identify the optimal geometry for the individual legs, and the length of the Bi2Te3 segments. We have segmented LAST(T) with Bi2Te3 and achieved contact resistivities of less than 10 µΩ•cm2. Here we give a detailed presentation on the procedures used in the fabrication of thermoelectric generators based on LAST, LASTT, and segmented with Bi2Te3 materials. We also present the output data on these generators. INTRODUCTION The need for efficient conversion of energy from heat to electricity has renewed interest in solid-state power generation, such as the use of thermoelectric materials to transfer heat to electricity. A good thermoelectric material is determined by its physical properties such as high electrical conductivity (σ), high Seebeck coefficient (S), and low thermal conductivity (κ). These properties define the dimensionless thermoelectric figure of merit, ZT = S2σT/κ, where T is the temperature and S2σ is refered to as the power factor. To fabricate a high efficiency thermoelectric module, various factors need to be considered, such as high ZT thermoelectric materials, low contact resistance, and low thermal loss. Nanostructured thermoelectric materials have been widely studied as high ZT thermoelectric materials [1,2,3,4]. The results have shown a very low thermal conductivity. Bulk samples in AgPbmSbTe2+m (LAST) and Ag(Pb1-xSnx)m SbTe2+m (LASTT) families of materials have been found to exhibit a high figure of merit near 700K [5,6,7]. Further details of utilizing LAST and LASTT to fabricate thermoelectric gene
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