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MM: Fachverband Metall- und Materialphysik

MM 22: Functional Materials I

MM 22.1: Vortrag

Dienstag, 27. März 2012, 10:15–10:30, H 1029

Optimizing thermoelectric Properties: Microstructure Analysis of AgPb₁₈SbTe₂₀ — •Susanne Perlt¹, Thomas Höche², Jayaram Dadda³, and Eckhard Müller³ — ¹Leibniz Institute of Surface Modification, Leipzig — ²Fraunhofer Institute for Mechanics of Materials, Halle — ³German Aerospace Center, Institute of Materials Research, Köln

Given the looming shortage of natural resources, there is a growing interest in renewable energy in recent years. The feasible recovery of waste-heat energy as it is generated by industrial and vehicle engines has led to increasing research interest in thermoelectrics (TE). In order to get TE materials with high performance, i.e. with a large figure of merit ZT, one needs to tune electronic and phononic properties. A promising candidate is the quaternary compound AgPb_mSbTe_2+m (Lead-Antimony-Silver-Tellurium, LAST-m). Its excellent performance is mainly based on a low value of the thermal conductivity κ - widely believed to be caused by self-assembled nanostructures. This study reports microstructure investigations at two different length scales. The micrometer scale was evaluated by SEM to analyze volume fraction and number of secondary phases as well as the impact of processing parameters on the homogeneity of bulk samples. Site-specific liftout of TEM lamellae from thermoelectrically characterised samples was made to investigate the structure on the nanometer scale. High-resolution TEM was performed to reveal shape and size distribution of nanoprecipitates. An attempt is made to derive a structure-property relationship.