Enhanced figure of merit in nanostructured (Bi,Sb)(2)Te(3) with optimized composition, prepared by a straightforward arc-melting procedure

Sb-doped Bi(2)Te(3) is known since the 1950s as the best thermoelectric material for near-room temperature operation. Improvements in material performance are expected from nanostructuring procedures. We present a straightforward and fast method to synthesize already nanostructured pellets that show an enhanced ZT due to a remarkably low thermal conductivity and unusually high Seebeck coefficient for a nominal composition optimized for arc-melting: Bi(0.35)Sb(1.65)Te(3). We provide a detailed structural analysis of the Bi(2−x)Sb(x)Te(3) series (0 ≤ x ≤ 2) based on neutron powder diffraction as a function of composition and temperature that reveals the important role played by atomic vibrations. Arc-melting produces layered platelets with less than 50 nm-thick sheets. The low thermal conductivity is attributed to the phonon scattering at the grain boundaries of the nanosheets. This is a fast and cost-effective production method of highly efficient thermoelectric materials.