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Title: Graphitic carbon nanospheres: A Raman spectroscopic investigation of thermal conductivity and morphological evolution by pulsed laser irradiation

Graphitic carbon nanospheres (GCNSs) were prepared by a unique acidic treatment of multi-walled nanotubes. Spherical morphology with a narrow size distribution was confirmed by transmission electron microscopy studies. The room temperature Raman spectra showed a clear signature of D- and G-peaks at around 1350 and 1591 cm{sup −1}, respectively. Temperature dependent Raman scattering measurements were performed to understand the phonon dynamics and first order temperature coefficients related to the D- and G-peaks. The temperature dependent Raman spectra in a range of 83–473 K were analysed, where the D-peak was observed to show a red-shift with increasing temperature. The relative intensity ratio of D- to G-peaks also showed a significant rise with increasing temperature. Such a temperature dependent behaviour can be attributed to lengthening of the C-C bond due to thermal expansion in material. The estimated value of the thermal conductivity of GCNSs ∼0.97 W m{sup −1} K{sup −1} was calculated using Raman spectroscopy. In addition, the effect of pulsed laser treatment on the GCNSs was demonstrated by analyzing the Raman spectra of post irradiated samples.
Authors:
; ; ;  [1]
  1. Department of Physics, University of Puerto Rico, San Juan, Puerto Rico 00936-8377 (United States)
Publication Date:
OSTI Identifier:
22492998
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; 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:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CARBON NANOTUBES; GRAPHITE; LASER RADIATION; MORPHOLOGY; PEAKS; PULSES; RAMAN EFFECT; RAMAN SPECTRA; RAMAN SPECTROSCOPY; RED SHIFT; SPHERICAL CONFIGURATION; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; THERMAL CONDUCTIVITY; THERMAL EXPANSION; TRANSMISSION ELECTRON MICROSCOPY