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Title: Size- and structure-dependence of thermal and mechanical behaviors of single-crystalline and polytypic superlattice ZnS nanowires

Molecular dynamics (MD) simulations are carried out to study the thermal and mechanical behaviors of single-crystalline wurtzite (WZ), zinc-blende (ZB), and polytypic superlattice ZnS nanowires containing alternating WZ and ZB regions with thicknesses between 1.85 nm and 29.62 nm under tensile loading. The wires analyzed have diameters between 1.77 nm and 5.05 nm. The Green-Kubo method is used to calculate the thermal conductivity of the wires at different deformed states. A non-equilibrium MD approach is used to analyze the thermal transport behavior at the interfaces between different structural regions in the superlattice nanowires (SLNWs). The Young's modulus and thermal conductivity of ZB nanowires are approximately 2%–12% and 23%–35% lower than those of WZ nanowires, respectively. The lower initial residual compressive stress due to higher irregularity of surface atoms causes the Young's modulus of ZB nanowires to be lower. The dependence of the thermal conductivity on structure comes from differences in phonon group velocities associated with the different wires. The thermal conductivity of polytypic superlattice nanowires is up to 55% lower than that of single-crystalline nanowires, primarily because of phonon scattering at the interfaces and the resulting lower effective phonon mean free paths for each structural region. As the periodic lengths (1.85–29.62 nm) and specimen lengthsmore » (14.81–59.24 nm) of SLNWs decrease, these effects become more pronounced, causing the thermal conductivity to further decrease by up to 30%.« less
Authors:
;  [1] ;  [2]
  1. School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)
  2. The George W. Woodruff School of Mechanical Engineering, School of Materials, Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States)
Publication Date:
OSTI Identifier:
22412875
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 21; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; APPROXIMATIONS; COMPUTERIZED SIMULATION; CUBIC LATTICES; INTERFACES; KUBO FORMULA; LOADING; MEAN FREE PATH; MOLECULAR DYNAMICS METHOD; MONOCRYSTALS; NANOWIRES; PERIODICITY; PHONONS; STRESSES; SUPERLATTICES; SURFACES; THERMAL CONDUCTIVITY; YOUNG MODULUS