Figure of merit enhancement in bismuth telluride alloys via fullerene-assisted microstructural refinement

Nanocomposite materials based on bismuth telluride with fullerene additions have been synthesized via ball milling and spark plasma sintering. The impact of fullerene addition upon the composites is studied with respect to both fullerene volume percentage and ball-mill duration. It is demonstrated that fullerenes can engage in significant microstructural refinement even when present in small quantities. The lattice thermal conductivity, electrical conductivity, Seebeck coefficient, and Hall coefficient are analyzed with a view to the impact of fullerene incorporation upon these properties. Fullerene-assisted microstructural refinement causes a decrease both in lattice thermal conductivity and electrical conductivity, but a corresponding increase in the Seebeck coefficient results in an enhancement in the figure of merit at low volume fractions. (C) 2011 American Institute of Physics. [doi:10.1063/1.3606547]