University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Thursday, March 19th 2015
1:25 pm:
Speaker: Eugene Levin, Iowa State
Subject: Recent findings for the Seebeck effect in thermoelectric tellurides

The Seebeck effect, known since 1821 and utilizing in thermoelectric materials to convert thermal to electrical energy, have been intensively studied and used in various applications, but there are indications that its fundamental understanding is still lacking. In order to better understand the Seebeck effect, we have used tellurides as model systems, common experimental methods (XRD, Seebeck coefficient, electrical resistivity, Hall effect, thermal conductivity, SEM, and EDS), and advanced method (125Te NMR to obtain the carrier concentration in tellurides via spin-lattice relaxation measurements). Several intriguing relations between the Seebeck coefficient, carrier concentration, composition, and rhombohedral lattice distortion have been established for GeTe alloyed with Ag and Sb (well-known high thermoelectric efficiency TAGS-m series). The Seebeck coefficient in some tellurides can be described by a common model with energy independent carrier scattering, but in some not. The latter can be explained by the effect from additional mechanism, likely energy filtering produced by [Ag+Sb] pairs in GeTe matrix. Our findings demonstrate that the Seebeck effect still holds surprises, and innovative research in the area of thermoelectric materials may help to elucidate and better utilize thermoelectric phenomena.

Faculty Host: Boris Shklovskii

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