Thermoelectric performance of thermally aged nanostructured bulk materials—a case study of lead chalcogenides. (June 2020)

• Record Type: Journal Article
• Authors: Byrnes, J.; Mitchell, D.R.G.; Aminorroaya Yamini, S.
• Is Part Of: Materials today physics. Volume 13(2020)
• Publication Date: 2020-06
• Subjects: Thermoelectric materials -- Thermal stability -- Multiphase -- Coarsening rate; Materials science -- Periodicals; Physics -- Periodicals; Electronic journals; 530.41
• DOI: 10.1016/j.mtphys.2020.100190
• Languages: English
• ISSNs: 2542-5293

Abstract

Abstract: The performance of nanostructured bulk thermoelectric material is shown to be enhanced because of phonon scattering. However, it is well-known that microstructures evolve by thermal aging, and their stability at the operating temperature is of vital importance to the success of the device. Here, we investigate the effect of long-term annealing (up to 8 weeks) on thermoelectric performance and microstructure of a high-efficiency Na-doped multiphase quaternary Pb chalcogenides. A z T of ~1.7–1.9 in the 700–850 K temperature range is achieved at all stages of thermal aging. A redistribution of Na-dopant between phases above ~630 K is believed to explain an increasing electrical resistivity in aged samples. This is balanced by a reduced total thermal conductivity as thermal aging time increases, possibly because of an increased concentration of nanoscale precipitates in samples aged for 8 weeks. Intermediate annealing of nanostructured lead chalcogenides has been shown to be an effective means of preparing thermally stable, high-performance thermoelectric materials. We have also determined the precipitates coarsening rate constant, k, to be 0.0206 μm/h 1/3 . Graphical abstract: Image 1 Highlights: Long-term annealing was investigated on a high efficient thermoelectric material. Despite an evolving microstructure, a z T of 1.7–1.9 is achieved at all stages of aging. The electrical resistivity was increased by aging at high temperatures. The total thermal conductivity was reduced by thermal aging. The precipitates coarsening rate constant, k, was determined to be 0.0206 μm/h 1/3 .