Rational design, high-yield synthesis, and low thermal conductivity of Te/Bi2Te3 core/shell heterostructure nanotube composites

Te/Bi2Te3 core/shell heterostructure nanotube (NT) composites with rough serrated interfaces, and hollow structures were designed and synthesized to enhance phonon scattering. A conventional two-step solution phase method was used to synthesize the mass products in high-yield. The external diameter and wall thickness of the NTs measured approximately 250 nm and 60 nm, and their lengths ranged from 7 mu m to 9 mu m. The hexagonal phase Te core, rhombohedral phase Bi2Te3 shell, hollow structure, and saw-toothed interface were accurately determined through X-ray diffraction, scanning electron microscopy and transmission emission microscopy. Relatively stable and low thermal conductivities (from 0.43 Wm(-1) K-1 to 0.46 Wm(-1) K-1) were obtained when the temperatures increased from 300 K to 400 K (near room temperatures). Finally, this research systematically examined the formation mechanisms based on the in situ growth method and the phonon scattering occurring in both the hollow structures and on the saw-toothed interface. (C) 2014 Elsevier B.V. All rights reserved.