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

作者：Dadda Jayaram^*; Mueller Eckhard; Perlt Susanne; Hoeche Thomas; Pereira Paula Bauer; Hermann Raphal P

来源：Journal of Materials Research, 2011, 26(15): 1800-1812.

DOI：10.1557/jmr.2011.142

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 degrees 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 0.8W/mK was also recorded. The low thermal conductivity coupled with a large Seebeck coefficient of similar to 320 mu V/K led to high ZT of about 1.05 at 425 degrees C for the sample annealed at 505 degrees C. These results also demonstrate that samples annealed above 450 degrees C for long term are more thermally stable than those treated at lower temperatures.

• 出版日期2011-8