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A2: Medium temperature materials
Lead telluride belongs to the most efficient thermoelectric materials in the medium temperature range. Especially the LAST (Lead-Antimony-Silver-Tellurium) system was found to have extraordinary thermoelectric properties and still one of the highest figures of merit for bulk materials.[1] While there were lots of efforts in the investigation of that system, the bismuth analogue BLST (Bismuth-Lead-Silver-Tellurium), when lead telluride is doped with the ternary compound AgBiTe2, has been poorly studied and was found to be less effective than the antimony-containing compound.[2]
For the first time, we investigated the influence of nanostructuring on the quarternary system PbTe-AgBiTe2, synthesized by mechanical alloying. The nanopowders were compacted to pellets via three different ways, such as cold pressing / annealing, hot pressing and short term sintering, to detect the impact of the compacting method and the resulting densities on the thermoelectric transport parameters, such as thermal conductivity, electrical conductivity and Seebeck coefficient. The electrical conductivity and the Seebeck coefficient were measured in a wide temperature range using two different techniques. The thermoelectric efficiency was compared to the one for bulk material.[2] In addition, the microstructure was studied via transmission electron microscopy.
[1] K.-F. Hsu, S. Loo, F. Guo, W. Chen, J. S. Dyck, C. Uher, T. Hogan, E. K. Polychroniadis, M. G. Kanatzidis, Science 2004, 303, 818 – 821.
[2] M.-K. Han, K. Hoang, H. Kong, R. Pcionek, C. Uher, K. M. Paraskevopoulos, S. D. Mahanti, M. G. Kanatzidis, Chem. Mater. 2008, 20, 3512 – 3520.
