Measurement of electrical resistance of thermoelectric materials with a temperature gradient using instant load-voltage analysis

Abstract

Among the properties of thermoelectric materials, electrical conductivity can be evaluated by measuring the resistance experimentally. However, thermoelectric materials have a high thermoelectric voltage due to their high Seebeck coefficient, which can cause measurement errors when using the four-wire method. This paper describes a new method for measuring the resistance of thermoelectric materials using temperature gradient. This method, instant load-voltage analysis (ILA), allows for measurement of the resistance of thermoelectric materials using the voltage induced by the Seebeck effect. The test sample was prepared with type E thermocouples, which have well-defined thermoelectric voltage with temperature. One side of the sample was kept at 20 °C; then the resistance was measured using the ILA method by increasing the temperature of the other side from 30 °C to 90 °C. The Fin model, a well-known heat transfer model, was used to determine the temperature of the sample with a temperature gradient. The measurement results were compared with the reference resistances measured by the four-wire method under constant temperature conditions. From the comparison, the sample resistance measured using the ILA method showed a good agreement (±0.2%) with the reference value.