Nanostructure and thermoelectric properties of p-type Bi0.5Sb1.5Te3 compound prepared by melt spinning technique

P-type Bi_0.5Sb_1.5Te₃ bulk material with fine nanostructure has been prepared by combining melt spinning technique with spark plasma sintering (SPS), and the effects of microstructure on the thermoelectric transport properties are investigated. Bi_0.5Sb_1.5Te₃ ribbons with fine nanostructure are obtained during the melt spinning process and the grain sizes of Bi_0.5Sb_1.5Te₃ are about 5-15 nm observed by High-resolution transmission electron microscopy. Such structure has great influence on thermoelectric transport properties of Bi_0.5Sb_1.5Te₃ compound. Compared with zone melting and directing SPS samples, the lattice thermal conductivity of the sample processed by melt spinning decreases significantly due to the intensive phonon scattering induced by the fine nanostructure. The greatest thermoelectric figure of merit (ZT) of 1.20 is obtained at 300K for the sample which is prepared by melt spinning with roller linear speed of 10 m/s.