O71] Study of thermal stability of advanced thermoelectrics by means of thermal analysis and Knudsen effusion mass spectrometry

Abstract

Thermoelectric materials have gained increased interest for their ability to exploit waste heat (renewable energy) and convert it to electricity. The research in the field of new perspective bulk and nano-structured (non-toxic) thermoelectrics is, therefore, of great importance for materials engineering in automotive and aerospace industry, electronics and other areas. Improvement of thermoelectric materials and production processes concern their thermoelectric properties, their thermodynamic and phase equilibria and also their long term thermal stability, which strongly depends on the content of volatile constituents as the current progressive materials contain elements like Cd, Zn, Sb, Sr and others. The temperature and phase stability of selected clathrates and skutterudites with high ZT-levels have been studied by means of thermal analysis (TA) and Knudsen effusion mass spectrometry (KEMS) performed on a Netzsch STA 409 CD/3/403/5/G apparatus, a specially-adapted type of the commercial STA 409 CD - QMS 403/5 Skimmer Coupling Instrument. The results from phase transformation measurements and measurements of evaporation characteristics of the volatile elements supported by microstructure observations and measurements of diffusion profiles are summarized and discussed in view of a full understanding of the degradation processes and knowledge on long term operation stability of the bulk and nano-structured thermoelectrics studied.