Microstructure and thermoelectric properties of n- and p-type Bi2Te3 alloys by rapid solidification processes

n-Type Bi2Te3-Bi2Se3 alloys with CdCl2 and p-type Bi2Te3+Sb2Te3 doped with 4 wt.% Te and were prepared by gas atomization and melt spinning processes, respectively, followed by sintering under vacuum. Microstructure and thermoelectric property of both the alloys were investigated as a function of doping quantity and sintering temperature from 400 to 500 degrees C, and compared with those of same alloys conventionally grown. Contrary to the microstructure formed in the directionally grown single crystal, no segregation of constituents like Te, Bi, Sb and Se was observed to form in the as rapidly solidified and sintered bodies. The highest thermoelectric figure of merit, calculated from the combination of Seebeck coefficient, electrical conduction, thermal conductivity, was obtained from the n-type specimen doped with 0.03 wt.% and sintered at 500 degrees C, while from the p-type sample sintered with the finest powders at 450 degrees C followed by annealed. (C) 2006 Elsevier B.V. All rights reserved.