ICT2014 Abstracts

In this study we show that Cu₂Se synthesized by the Self-propagating High-temperature Synthesis (SHS), the technique applied to the preparation of thermoelectric materials for the first time, satisfies all the criteria above and results in a structurally robust material with outstanding thermoelectric properties typified by the dimensionless figure of merit ZT = 1.2 at 800 K, and better than 1.8 at 1000 K. The key parameters of the SHS processing such as the ignition temperature and the velocity of the combustion front were determined and their correlation with the microstructure was investigated. Beyond the excellent thermoelectric performance, the SHS synthesis followed by Spark Plasma Sintering (SPS) cuts the preparation time from a few days to less than one hour and can be scaled up to kilogram quantities of materials. Moreover, the resulting Cu₂Se is purified by the SHS process, the final product is perfectly stoichiometric and significantly more stable than Cu₂Se prepared by other methods, and its thermoelectric properties are unchanged after three weeks of annealing at 800 K. The efficiency of a prototype couple made from this p-type Cu₂Se material in combination with the state-of-the-art n-type Yb_0.25Co₄Sb₁₂ is about 12% higherthan that of all skutterudite-based p-Ce_0.9Fe_3.4Co_0.6Sb₁₂/n-Yb_0.25Co₄Sb₁₂ couple. The application of the SHS method opens a new avenue for ultra-fast, low cost, mass production fabrication of efficient thermoelectric materials.