Simultaneous measurement of the Seebeck coefficient and thermal diffusivity for bulk thermoelectric materials

Abstract

We simultaneously measured the Seebeck coefficient and thermal diffusivity of a rectangular parallelepiped bulk thermoelectric material. We used one-dimensional heat conduction equation to show that a periodic heat cycle produces not only the thermoelectromotive force but also a certain phase shift angle between the edge and intermediate points of a sample along the length of the material. Based on the equation of the modified Angström method, an experiment at 300 K was performed using NIST standard material (SRM 3451, Bi2Te3 material) to measure the Seebeck coefficient and thermal diffusivity. The measured Seebeck coefficient was −231 ± 3 µV/K, which corresponds to the published value. Using the same experimental setup as that for the thermal diffusivity measurement, the dependence of the phase shift angle on frequency was measured from 5 mHz to 10 Hz for the phase shift angle from −8.2 to −450°. The estimated thermal diffusivity was (1.53 ± 0.05) × 10−6 m2/s. We conclude that the modified Angström method can be used to measure the Seebeck coefficient and thermal diffusivity simultaneously.