Determination of the Thermal Conductivity based on a Thermal Capacitor Model

This paper describes a method which enables the calculation of the thermal conductivity kappa of thermoelectric materials during a simultaneous measurement of the Seebeck coefficient S and the electrical conductivity sigma based on a time-resolved measurement of temperature difference across the sample. The described method bases upon the availability of one known external value of kappa with low uncertainty. The described method takes advantage of the well-known thermal capacitor model. The simultaneous determination of S, sigma and kappa enables to calculate the thermoelectric figure of merit ZT = S-2 sigma T/kappa of the specimen in one measurement cycle. This results in lower uncertainties of ZT except when if S, sigma and kappa are measured separately. The measured values of the thermal conductivity and the resulting thermoelectric figure of merit of metallic samples (ISOTAN (R), steel) and of two semiconducting samples (Bi-PbTe, FeSi2) are presented. (C) 2015 Elsevier Ltd. All rights reserved.