A simple differential steady-state method to measure the thermal conductivity of solid bulk materials with high accuracy

Journal Article · Thu Feb 20 00:00:00 EST 2014 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4865111· OSTI ID:1385072

Kraemer, D. ^[1]; Chen, G. ^[1]

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1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

Accurate measurements of thermal conductivity are of great importance for materials research and development. Steady-state methods determine thermal conductivity directly from the proportionality between heat flow and an applied temperature difference (Fourier Law). Although theoretically simple, in practice, achieving high accuracies with steady-state methods is challenging and requires rather complex experimental setups due to temperature sensor uncertainties and parasitic heat loss. We developed a simple differential steady-state method in which the sample is mounted between an electric heater and a temperature-controlled heat sink. Our method calibrates for parasitic heat losses from the electric heater during the measurement by maintaining a constant heater temperature close to the environmental temperature while varying the heat sink temperature. This enables a large signal-to-noise ratio which permits accurate measurements of samples with small thermal conductance values without an additional heater calibration measurement or sophisticated heater guards to eliminate parasitic heater losses. Additionally, the differential nature of the method largely eliminates the uncertainties of the temperature sensors, permitting measurements with small temperature differences, which is advantageous for samples with high thermal conductance values and/or with strongly temperature-dependent thermal conductivities. In order to accelerate measurements of more than one sample, the proposed method allows for measuring several samples consecutively at each temperature measurement point without adding significant error. We demonstrate the method by performing thermal conductivity measurements on commercial bulk thermoelectric Bi₂Te₃ samples in the temperature range of 30–150 °C with an error below 3%.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Solid-State Solar-Thermal Energy Conversion Center (S3TEC)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0001299; FG02-09ER46577
• OSTI ID: 1385072
• Journal Information: Review of Scientific Instruments, Vol. 85, Issue 2; Related Information: S3TEC partners with Massachusetts Institute of Technology (lead); Boston College; Oak Ridge National Laboratory; Rensselaer Polytechnic Institute; ISSN 0034-6748
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

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