Synthesis of narrow band gap SnTe nanocrystals: nanoparticles and single crystal nanowires via oriented attachment

SnTe nanocrystals with different shapes and sizes are synthesized by a simple and facile method. The length of the fatty chain in amine has an important effect on the shape and size of SnTe nanocrystals. When oleylamine (OLA) is used as ligand, SnTe nanoparticles with size of 4 nm and high crystallinity are produced. However, when octylamine (OTA) is used as ligand, larger SnTe nanoparticles with low crystallinity are achieved, which would transform into single crystal SnTe nanowires with increasing reaction time. The driving force of shape evolution of SnTe nanocrystals is reducing the high surface free energy. An oriented attachment mechanism is proposed to explain the transition from nanoparticles to nanowires, and oriented attachment of nanoparticles to single crystal nanowires is proposed to reduce the interface energy by the greatest amount.