Thermal property tuning in aligned carbon nanotube films and random entangled carbon nanotube films by ion irradiation
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843 (United States)
- Department of Nuclear Engineering, Texas A&M University, College Station, Texas 77843 (United States)
- The Alan G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75080 (United States)
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.
- OSTI ID:
- 22482239
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 15 Vol. 107; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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