Microstructures and nanostructures in long-term annealed AgPb18SbTe20 (LAST-18) compounds and their influence on the thermoelectric properties

Abstract

This article reports on the role of annealing on the development of microstructure and its concomitant effects on the thermoelectric properties of polycrystalline AgPbmSbTe2+m (m = 18, lead–antimony–silver–tellurium, LAST-18) compounds. The annealing temperature was varied by applying a gradient annealing method, where a 40-mm-long sample rod was heat treated in an axial temperature gradient spanning between 200 and 600 °C for 7 days. Transmission electron microscopy investigations revealed Ag2Te nanoparticles at a size of 20–250 nm in the matrix. A remarkable reduction in the thermal conductivity to as low as 0.8 W/mK was also recorded. The low thermal conductivity coupled with a large Seebeck coefficient of ∼320 μV/K led to high ZT of about 1.05 at 425 °C for the sample annealed at 505 °C. These results also demonstrate that samples annealed above 450 °C for long term are more thermally stable than those treated at lower temperatures.

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ACKNOWLEDGMENTS

The authors thank the Federal Ministry for Education and Research (BMBF), Germany “Werkstofftechnologien von morgen—Wissenschaftliche Vorprojekte in Werkstoff—und Nanotechnologien,” for funding this research study (03X3540A). Raphael Hermann acknowledges the Helmholtz-Gemeinschaft Deutscher Forschungszentren for funding of the Young Investigator Group “Lattice dynamics in emerging functional materials.” The authors also thank Dr. Peter Werner for his valuable contribution in HRTEM investigations performed at Max Planck Institute, Halle, Germany.

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Correspondence to Jayaram Dadda.

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Dadda, J., Müller, E., Perlt, S. et al. Microstructures and nanostructures in long-term annealed AgPb18SbTe20 (LAST-18) compounds and their influence on the thermoelectric properties. Journal of Materials Research 26, 1800–1812 (2011). https://doi.org/10.1557/jmr.2011.142

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