Preparation and Microstructure Control of One-Dimension Core-Shell Heterostructure of Te/Bi, Te/Bi2Te3 by Microwave Assisted Chemical Synthesis

Abstract

Microstructure engineering of thermoelectric materials can resolve the conflicts of electrical and thermal transports. Especially, one-dimensional structure can obviously improve the thermoelectric figure of merit because of its crystal anisotropy and strong quantum confinement effect. In this paper, the Te nanowires, one-dimensional core-shell heterostructure of Te/Bi and Te/Bi2Te3 were controlled synthesized by microwave assisted chemical synthesis. The effect of PVP concentration and reductant dropping rate on the microstructure of the Te nanowires were investigated. The experimental results showed that with increasing the amount of PVP, the Te nanowires got less crystallinity and its surface become more rough due to its steric hindrance effect. With decreasing reductant dropping rate, the longer and thiner Te nanowires were obtained. Epitaxial growth can describe the relation of core Te and shell Bi (or Bi2Te3). It has been found that Bi shell uniformly surrounded around Te nanowires core, but Bi2Te3 sheets were perpendicular to the c-axis of Te nanowires. The different core-shell heterostructure structure can be obtained by adjusting reaction conditions and controlling diffusion kinetics of Te and Bi.