ICT2014 Abstracts

The effort to increase thermoelectric properties has been mostly focused on reduing the thermal conductivity by the phonon scattering at grain boudaries which can be enhanced by nanostructuring. This nanostructuring has been usually achieved by the combination of sintering with high energy ball milling, chemical or hydrothermal method. However, these isotropic nanostructuring techniques have a disadvantage of occurring the charge carrier scattering as well as the phonon scattering at grain boudaries, even though the electrical conductivity could be increased in isotropic nanostructures by the quantum confinement effect. In order to reduce carreir scattering with maintaining the phonon scattering, the internal nanostructure has to be ordered anisotropic.

In this research, we synthesized (Bi,Sb)₂Te₃ alloys with maximizing anisotropic internal structure. Te nanowires were massively synthesized from TeO₂ powders by chemical method at high temperature. Massive Te nanowires were used as templates for ternary BiSbTe alloying. Bi and Sb nanopowders were obtained by conventional high energy ball milling (attrition mills). These three elements were then sintered with SPS (Spark Plasma Sintering). The stoichiometric (Bi,Sb)₂Te₃ alloy and anisotropic internal structures were confirmed in the sintered samples by XRD analysis and TEM observations