Work

Fabrication of Bi 2 Te 3− x Se x nanowires with tunable chemical compositions and enhanced thermoelectric properties

Year: 2016

Type: article

Abstract: Uniform Bi 2 Te 3− x Se x nanowires (NWs) with tunable components are synthesized by a modified solution method free of any template, and inter-diffusion mechanism is proposed for the growth and transformation of ternary nanowires. Spark plasma sintering is adopted to fabricate the pellets of Bi 2 Te 3− x Se x NWs and thermoelectric transport properties are measured. As compared to Bi 2 Te 3 pellets, Se doping results in lowered electrical conductivity because of the reduced carrier concentration, both the Seebeck coefficient and the power factor are enhanced substantially. The Bi 2 Te 2.7 Se 0.3 pellet exhibits the highest power factor at room temperature as a result of optimized carrier concentration (4.37 × 10 19 cm −3 ) and mobility (60.22 cm 2 V −1 s −1 ). As compared to Bi 2 Te 3 , the thermal conductivity of Bi 2 Te 3− x Se x is lowered owing to the enhanced phonon scattering by dopants and grain boundaries. As a result, the ZT value at 300 K is substantially improved from 0.045 of Bi 2 Te 3 to 0.42 of Bi 2 Te 2.7 Se 0.3 . It is suggested that Se doping is an effective way to enhance the thermoelectric performance of Bi 2 Te 3 based materials.

Source: Nanotechnology

DOI: 10.1088/1361-6528/aa55e7