Effects of Cooling Rate on Thermoelectric Properties of n-Type Bi2(Se0.4Te0.6)3 Compounds

A series of Bi-2(Se0.4Te0.6)(3) compounds were synthesized by a rapid route of melt spinning (MS) combined with a subsequent spark plasma sintering (SPS) process. Measurements of the Seebeck coefficient, electrical conductivity, and thermal conductivity were performed over the temperature range from 300 K to 520 K. The measurement results showed that the cooling rate of melt spinning had a significant impact on the transport properties of electrons and phonons, effectively enhancing the thermoelectric properties of the compounds. The maximum ZT value reached 0.93 at 460 K for the sample prepared with the highest cooling rate, and infrared spectrum measurement results showed that the compound with lower tellurium content, Bi-2(Se0.4Te0.6)(3), possesses a larger optical forbidden gap (E (g)) compared with the traditional n-type zone-melted material with formula Bi-2(Se0.07Te0.93)(3). Our work provides a new approach to develop low-tellurium-bearing Bi2Te3-based compounds with good thermoelectric performance.