Thermoelectric standardisation - Reference materials and characterisation

Abstract

Thermoelectric materials for working temperatures between 300 K and 1000 K become continuously more important for energy recuperation applications. The efficiency is determined by the transport properties (electrical and thermal conductivity and Seebeck coefficient), which form the known thermoelectric figure of merit ZT. The thorough determination of ZT represents the basis for the assessment of thermoelectric materials research. Due to different continuing difficulties measurement errors distinctly higher than 15% can be observed repeatedly, which is still too high for an industrial benchmark and deficient for many scientific investigations and technological developments. Against this background a project was launched in 2011 together with the Fraunhofer Institute of Physical Measurement Techniques (IPM, Freiburg), the Department Temperature of the Physikalisch-Technische Bundesanstalt (PTB, Berlin) and the company Netzsch Gerätebau GbmH (Selb). The aim of the project "Thermoelectric Standardisation" (TEST) is to minimise the measurement uncertainties and to develop traceable, high-accurate thermoelectric characterisation techniques and thermoelectric reference materials for the mentioned temperature range. Here we initially present the project to the thermoelectric society and want to give a survey on the planned activities and the current status of the contributions of the German Aerospace Center (DLR, Cologne).