Apparatus for the high temperature measurement of the Seebeck coefficient in thermoelectric materials

Abstract

The Seebeck coefficient is a physical parameter routinely measured to identify the potential thermoelectric performance of a material. However, researchers employ a variety of techniques, conditions, and probe arrangements to measure the Seebeck coefficient, resulting in conflicting materials data. To compare and evaluate these methodologies, and to identify optimal Seebeck coefficient measurement protocols, we have developed an improved experimental apparatus to measure the Seebeck coefficient under multiple conditions and probe arrangements (300 K-1200 K). This paper will describe in detail the apparatus design and instrumentation, including a discussion of its capabilities and accuracy as measured through representative diagnostics. In addition, this paper will emphasize the techniques required to effectively manage uncertainty in high temperature Seebeck coefficient measurements.

Synthesis, transport properties, and electronic structure of Cu2CdSnTe4

“…23 High temperature S and q were measured with a custom-designed and constructed apparatus at NIST (expanded uncertainty of 0.9% and 1.1% for S and q, respectively). 24,25 High temperature thermal diffusivity measurements were made under flowing Ar with an Anter flashline system. The uncertainty in the thermal diffusivity measurements was $5%.…”

Protocols for the high temperature measurement of the Seebeck coefficient in thermoelectric materials

“…One shield rests between the lower and upper probe to trace the temperature along the sample, while the second shield encloses the entire probe along the axis of the furnace. Individual thermal fluctuation for each thermocouple at 295 K is below 10 mK and the deviation between each thermocouple temperature is less than 60 mK [15]. The thermal stability is typically between 20 and 40 mK at higher temperatures.…”

“…The salient features are restated below for completeness. Reference [15] describes the primary components in more detail.…”

Simple design for Seebeck measurement of bulk sample by 2-probe method concurrently with electrical resistivity by 4-probe method in the temperature range 300–1000 K

“…Martin et al recently compared the results obtained from the 2-probe and 4-probe methods [20,40]. The 4-probe method was found to yield Seebeck coefficient values higher than the 2-probe method, with the difference being proportional to the temperature difference between the sample and surroundings and reaching that difference 14% at 900 K [26,40]. Such discrepancy in Seebeck measurement can itself introduce error of about 28 % at 900 K in power factor estimation.…”

“…Depending on the behavior of temperature difference with respect to observation, timescale differential methods can be classified into three categories: steady-state (DC) [25][26][27][28] quasi-steady-state (qDC) [25,29,30] and transient (AC) [31][32][33]. Under steady-state conditions, V is recorded against stabilized T and the Seebeck coefficient is often calculated from the linear fit of multiple Vs and Ts to avoid extraneous offset voltage.…”