Note: High resolution alternating current/direct current Harman technique

Chavez, Ruben; Becker, A.; Bartel, M.; Kessler, V.; Schierning, Gabi; Schmechel, Roland

doi:10.1063/1.4825118

Cited by 8 publications

(3 citation statements)

References 7 publications

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“…Determination of ZT is one of the major activities in thermoelectric research. In general, ZT can be determined by measuring α , ρ, and λ separately [1][2][3][4] or directly using the Harman method [5,6] and its derivatives [7,8]. The advantage of the Harman method is that it can determine ZT directly from simply measuring its ac and dc responses.…”

Section: Introductionmentioning

confidence: 99%

Principle of determining thermoelectric properties based onI–Vcurves

Min

2014

Meas. Sci. Technol.

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This paper describes a measurement principle of determining thermoelectric properties based on obtaining current–voltage (I–V) curves under two different operating conditions: (1) constant temperature difference and (2) constant thermal input flux. In addition to thermoelectric figure-of-merit, other thermoelectric properties including the Seebeck coefficient, electrical resistivity and thermal conductivity can also be derived from I–V measurements. An advantage of this technique is its ability to detect the influence of the Thomson effect and to characterize the segmented thermoelectric structures due to the fact that a measurement can be taken under a large temperature difference in a closed circuit condition. Furthermore, it has a potential to achieve high measurement accuracy because the error due to the contact resistance is eliminated.

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Section: Introductionmentioning

confidence: 99%

Principle of determining thermoelectric properties based onI–Vcurves

Min

2014

Meas. Sci. Technol.

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“…One critical point when using this method is to extract V Ohm from the total voltage. Chaves et al [59] realized high resolution (±0.008) module ZT characterization from the ohmic resistance measured by using AC current flow at optimized frequency. In this method, an appropriate operation frequency is crucial as it should be high enough to avoid Peltier induced voltages but low enough to prevent any reactance in the circuit which could affect the measurement.…”

Section: Harman Methods and Impedance Spectroscopy Approachmentioning

confidence: 99%

Module-level design and characterization of thermoelectric power generator

Zhu¹,

Bai²,

Kim³

et al. 2022

Chinese Phys. B

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Thermoelectric power generation provides us the unique capability to explore the deep space and holds promise for harvesting the waste heat and providing a battery-free power supply for IoTs. The past years have witnessed massive progress in thermoelectric materials, while the module-level development is still lagged behind. We would like to shine some light on the module-level design and characterization of thermoelectric power generators (TEGs). In the module-level design, we review material selection, thermal management, and the determination of structural parameters. We also look into the module-level characterization, with particular attention on the heat flux measurement. Finally, the challenge in the optimal design and reliable characterization of thermoelectric power generators is discussed, together with a calling to establish a standard test procedure.

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“…Accurate evaluation of thermoelectric figure-of-merit, ZT = α 2 T / ρk , is of great importance to the development of thermoelectric materials, where α is the Seebeck coefficient, ρ is the electrical resistivity, k is the thermal conductivity, and T is the absolute temperature 1 2 3 4 5 6 . There are two common ways to determine ZT : first, independent evaluations of thermoelectric properties 4 6 7 8 9 ; second, direct ZT measurements by the Harman method 1 2 5 10 11 12 13 . The first method is prevalent, since measuring each of the thermoelectric properties helps to understand the associated electrical and thermal transport phenomena, and the instruments for these measurements are more common.…”

mentioning

confidence: 99%

Correction of the Electrical and Thermal Extrinsic Effects in Thermoelectric Measurements by the Harman Method

Kang

Roh

Lee

et al. 2016

Sci Rep

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Although the Harman method evaluates the thermoelectric figure-of-merit in a rapid and simple fashion, the accuracy of this method is affected by several electrical and thermal extrinsic factors that have not been thoroughly investigated. Here, we study the relevant extrinsic effects and a correction scheme for them. A finite element model simulates the electrical potential and temperature fields of a sample, and enables the detailed analysis of electrical and thermal transport. The model predicts that the measurement strongly depends on the materials, sample geometries, and contact resistance of the electrodes. To verify the model, we measure the thermoelectric properties of Bi2-Te3 based alloys with systematically varied sample geometries and either with a point or a surface current source. By comparing the model and experimental data, we understand how the measurement conditions determine the extrinsic effects, and, furthermore, able to extract the intrinsic thermoelectric properties. A correction scheme is proposed to eliminate the associated extrinsic effects for an accurate evaluation. This work will help the Harman method be more consistent and accurate and contribute to the development of thermoelectric materials.

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Note: High resolution alternating current/direct current Harman technique

Cited by 8 publications

References 7 publications

Principle of determining thermoelectric properties based onI–Vcurves

Principle of determining thermoelectric properties based onI–Vcurves

Module-level design and characterization of thermoelectric power generator

Correction of the Electrical and Thermal Extrinsic Effects in Thermoelectric Measurements by the Harman Method

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