Impact of parasitic thermal effects on thermoelectric property measurements by Harman method

Beomjin Kwon, Seung Hyub Baek, Seong Keun Kim, Jin Sang Kim

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Harman method is a rapid and simple technique to measure thermoelectric properties. However, its validity has been often questioned due to the over-simplified assumptions that this method relies on. Here, we quantitatively investigate the influence of the previously ignored parasitic thermal effects on the Harman method and develop a method to determine an intrinsic ZT. We expand the original Harman relation with three extra terms: heat losses via both the lead wires and radiation, and Joule heating within the sample. Based on the expanded Harman relation, we use differential measurement of the sample geometry to measure the intrinsic ZT. To separately evaluate the parasitic terms, the measured ZTs with systematically varied sample geometries and the lead wire types are fitted to the expanded relation. A huge discrepancy (∼28%) of the measured ZTs depending on the measurement configuration is observed. We are able to separately evaluate those parasitic terms. This work will help to evaluate the intrinsic thermoelectric property with Harman method by eliminating ambiguities coming from extrinsic effects.

Original languageEnglish (US)
Article number045108
JournalReview of Scientific Instruments
Volume85
Issue number4
DOIs
StatePublished - Apr 2014
Externally publishedYes

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ASJC Scopus subject areas

  • Instrumentation

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