Enhanced thermoelectric performance of nanostructured CNTs/BiSbTe bulk composite from rapid pressure-quenching induced multi-scale microstructure

A simple and rapid physical “top-down” pressure-quenching nanostructuring method at high pressure and high temperature (HPHT) was proposed to synthesize in situ nanostructured bulk composite material. The multiple and multiscale nanostructures can be spontaneously formed by rapid pressure-quenching from the melt, including the nanocrystals and the lattice disorders. Besides, carbon nanotubes (CNTs) were also dispersed into the material to have more interfaces. The thermal conductivity by the HPHT quenching method is lower than that by other nanostructuring methods, and the minimum value of the material is 0.74 Wm −1 K −1 at 373 K. The Seebeck coefficient is improved by low energy carrier filtering at grain boundaries and phase interfaces when the electrical conductivity is less deteriorated. The maximum ZT of Bi 0.4 Sb 1.6 Te 3 bulk material with 0.1 wt.% CNTs is 1.42 at 373 K and 4 GPa. The HPHT quenching method can provide a promising alternative to obtain nanostructured bulk composite materials with the enhanced thermoelectric performance.