Characterization of carbon nanotubes synthesized using magnetic field assisted arc discharge technique

Abstract

The unique properties of multi-walled carbon nanotubes (mwcnts) attract enormous attentions as promising nanomaterials for numerous applications. in this research, the growth of mwcnts using direct current (dc) arc discharge plasma under magnetic field effect in different ambient environments and pressures were investigated. arc plasma was generated inside a vacuum chamber by contact ignition between two graphite rods. a dc power supply was used to supply an arc current of 70 a and a voltage of 12 v across the graphite rods. magnetic field was applied in transverse and axial configurations with field strength of 30 mt. arc discharge experiments were conducted in air, hydrogen and argon environment for different ambient pressures of 10-2, 10-1, 1, 101 and 102 mbar. the structural and physical properties of mwcnts were characterized using transmission electron microscopy, field emission scanning electron microscopy, raman spectroscopy, fourier transform infra-red spectroscopy and x-ray diffractometry. results showed that mwcnts growth in arc discharge plasma was significantly influenced by the ambient environment, gas pressure, axial and transverse magnetic field. the applied transverse magnetic field on arc discharge plasma enhanced the growth of mwcnts with smaller tube dimeter. the axial magnetic field on the other hand allowed the growth of long tubular structure with lesser impurities as observed under electron microscope. results from raman spectroscopy showed that high rise of g band as compared with d band indicates high rise of graphitic structure of mwcnts. the mwcnts quality was measured in terms of intensity ratio of the peak d band to the peak g band. high quality mwcnts with less defective sites were obtained for sample prepared in hydrogen environment. the increase in the length of the mwcnts was observed for sample prepared in the presence of inert gas argon. in conclusion, high quality mwcnts were successfully synthesized using magnetic field assisted arc discharge technique.