Measurement setup fpr simultaneous determination of electrical conductivity, Hall coefficient and Seebeck coefficient

Kurzfassung

Thermoelectric materials can convert heat directly into usable electrical energy. An important aim in thermoelectric research is to find and optimize suitable materials and improve their performance to get higher efficiency. For a complete characterization it is in general required to do several different measurements in different apparatuses which can be challenging and time consuming. Therefore we developed a measurement system that can measure three of the thermoelectric key quantities (electrical conductivity, Seebeck- and Hall coefficient) simultaneously from room temperature up to 1000K, which is a typical temperature region for many potential applications of these materials. All three quantities are coupled via the charge carrier concentration and therefore a simultaneous measurement is important for a deep insight in the charge carrier transport in the sample. This is particularly important for thermally instable materials, where consecutive measurements can easily lead to misinterpretations. Four sheathed thermocouples arranged in a van der Pauw geometry are pressed by small springs on a round sample for electrical contact. This special arrangement allows for the electrical measurements, while the thermocouples allow for a determination of the Seebeck coefficient if an additional temperature gradient is applied. We will discuss technical details, features and limitations of the setup.