Nanostructures and enhanced thermoelectric properties in Ce-filled skutterudite bulk materials

摘要

The nanostructures induced by uniaxial compression in Ce_(0.29)Fe_(1.40)Co_(2.60)Sb_(11.24) bulk thermoelectric material is reported. High-resolution transmission electron microscope images reveal that the nanostructures consist of Ce_(0.31)Fe_(1.38)Co_(2.62)Sb_(11.56) crystals and Fe_(0.34)Co_(0.66)Sb_(1.99) minicrystal/ noncrystal with grain sizes about 5-20 nm. It is shown that the Seebeck coefficient is increased by 21%, the phonon thermal conductivity is reduced by 19%, while the electrical conductivity rises slightly at 300 K. This leads to a surprising increase in the power factor by 51%. The significant increase of Seebeck coefficient and the remarkable reduction of phonon thermal conductivity are believed to be due to quantum effect and size effect of the nanostructures, respectively.