The ZT coefficient describes the performance of a thermoelectric material. ZT is typically calculated from the thermal and electrical conductivity and the Seebeck coefficient . These three properties are measured separately, and each measurement is subject to a certain degree of error.
The Harman method allows for the direct measurement of ZT in a single measurement: The voltage measured when a current is applied to a thermoelectric material consists of two components: the ohmic drop and the thermoelectric voltage. Dividing one by the other yields ZT.
The NIST (SRM 3451)™ -Bi₂Te₃ bismuth telluride reference material was analyzed using the Harman method on the LINSEIS LSR platform. The measurement clearly shows the typical voltage distribution at a single temperature measurement point. In this case, the ZT value at room temperature can be easily calculated by relating the ohmic voltage drop to the thermoelectric voltage drop. A ZT value of 0.50 was determined at room temperature.
Appropriate measuring device
