ICT2014 Abstracts

In the study, Single-phase Bi₂Te_3-xSe_x(x=0-3) alloys have been successfully obtained by the Self-propagating-High-temperature-Synthesis (SHS) technique. After the ignition at one end of compacted pellet of Bi, Te and Se powder mixture, the reaction can sustain relying on the heat released by the chemical reaction and self-propagate to the other end, which significantly shortened the synthesis period into seconds . Systematic study of the thermodynamics and kinetics of the SHS process for Bi₂Te₃ and Bi₂Se₃ has been carried out and results show that the combustion temperature, adiabatic combustion temperature and speed of combustion wave were 723 K, 861 K and 6 mm / s for Bi₂Te₃ , and 740 K, 995 K and 6 mm / s for Bi₂Se₃, respectively. Single-phase Bi₂Te_3-xSe_x bulk material can be obtained within 20 min by SHS combined with plasma activation sintering (PAS), greatly shortening the preparation time and cost compared with the commercial zone melting method. The Bi₂Se_2.4Se_0.6 bulk material shows a maximum ZT value 0.81 at 398 K. SHS-PAS technique demonstrated here opens a new approach for ultra- fast low-cost preparation technique for thermoelectric materials like Bi-Te-Se alloys and other systems as well.