Simple, reversible gradient Seebeck coefficient measurement system for 300-600K with COMSOL simulations.

Abstract

Seebeck measurement is a crucial step for characterizing thermoelectric samples, as measuring the accurate value with a simpler system design is challenging. Here, we report a simple design of the Seebeck coefficient measurement system, which can measure the thermo-emf (Seebeck coefficient) of the sample, under a limited temperature range of 300-600K. Unlike the majority of the reported instrumental designs, the system does not have a hot walled chamber. The sample is sandwiched between two brass block supported heaters, which are controlled separately. Thus, this type of system is suitable for a window of the temperature range near room temperature. In this paper, we report the system that can measure the Seebeck coefficient up to 600K. The heaters touch the sample through 1mm thick silver caps, which offer insignificant thermal resistance and a stable temperature, as seen through experiment as well as COMSOL simulations. A typical sample has, at maximum, a diameter of 10mm and a thickness of 2-3mm. A reversible temperature gradient is applied in quasi-static direct current mode. By virtue of its design, the sample holder ensures a minimum thermal and electrical contact resistance during a measurement cycle. The combination of metals used for measurement (Ag and Cu) shows negligible junction contribution. The variance up to ±2% and accuracy up to 8% at a high temperature have been obtained using calibration sample reference data of state-of-the-art commercial systems.