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Title: Thermal property tuning in aligned carbon nanotube films and random entangled carbon nanotube films by ion irradiation

Ion irradiation effects on thermal property changes are compared between aligned carbon nanotube (A-CNT) films and randomly entangled carbon nanotube (R-CNT) films. After H, C, and Fe ion irradiation, a focusing ion beam with sub-mm diameter is used as a heating source, and an infrared signal is recorded to extract thermal conductivity. Ion irradiation decreases thermal conductivity of A-CNT films, but increases that of R-CNT films. We explain the opposite trends by the fact that neighboring CNT bundles are loosely bonded in A-CNT films, which makes it difficult to create inter-tube linkage/bonding upon ion irradiation. In a comparison, in R-CNT films, which have dense tube networking, carbon displacements are easily trapped between touching tubes and act as inter-tube linkage to promote off-axial phonon transport. The enhancement overcomes the phonon transport loss due to phonon-defect scattering along the axial direction. A model is established to explain the dependence of thermal conductivity changes on ion irradiation parameters including ion species, energies, and current.
Authors:
 [1] ; ;  [2] ; ;  [3] ;  [1] ;  [4]
  1. Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843 (United States)
  2. Department of Nuclear Engineering, Texas A&M University, College Station, Texas 77843 (United States)
  3. The Alan G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75080 (United States)
  4. (United States)
Publication Date:
OSTI Identifier:
22482239
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 15; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CARBON NANOTUBES; DEFECTS; FILMS; FOCUSING; HEATING; ION BEAMS; IRON IONS; IRRADIATION; PHONONS; QUANTUM ENTANGLEMENT; RANDOMNESS; SCATTERING; SIGNALS; THERMAL CONDUCTIVITY; TRAPPING