Chemical synthesis of Bi(0.5)Sb(1.5)Te3 nanocrystals and their surface oxidation properties.

Bismuth-antimony-telluride alloy, Bi(0.5)Sb(1.5)Te3, nanocrystals (NCs) have been synthesized by direct chemical solution synthesis, in which the bismuth and antimony precursors, dissolved in a phenyl ether solution and coordinated with dodecanethiol, directly reacted with tellurium in trioctylphosphine. Transmission electron microscopy and X-ray diffraction (XRD) were used for the structure and morphology characterization of these NCs. Their XRD pattern evolution indicated that the reaction temperature plays a critical role in alloying and crystallization of Bi(0.5)Sb(1.5)Te3 NCs. X-ray photoelectron spectrometry was used to study the alloy states and surface oxidation. It is found that the choice of the capping ligands can be important and useful in protecting against the surface oxidation of Bi2Te3-type thermoelectrical nanomaterials.