Development and Applications of Non-destructive Screening Tools for Thermoelectric Materials at NIST

Abstract

The increased research and development of thermoelectric materials for energy conversion applications is driven primarily by the need for improved efficiency in the global utilization of energy resources. To facilitate the search for higher efficiency thermoelectric materials, we have developed a suite of complimentary high-throughput screening systems for performing thermoelectric metrology on combinatorial thin films. These custom capabilities include a facility for combinatorial thin film synthesis and suite of tools for screening the Seebeck coefficient, electrical resistance, and thermal conductivity of combinatorial films. The room temperature Seebeck coefficient and resistance are measured via an automated multiprobe apparatus, thus obtaining the power factor, S2σ (where S = Seebeck coefficient, σ = electrical conductivity). In addition, we are developing a high temperature (>300 K) power factor screening tool. Thermal effusivity (to calculate the thermal conductivity) is measured using a frequency domain thermo-reflectance technique. Using these tools, we are capable of performing power factor and thermal conductivity measurements on 1000 distinct sample-points within 6 hours for each instrument. This paper will detail several application examples using these tools on thermoelectric materials, including composition-spread films, conventional thin films, bulk ceramics, ribbons/tapes, and on single crystals.