Electron Irradiation Induced Structural Changes in Nickel Nanorods Encapsulated in Carbon Nanotubes

Nickel nanorods encapsulated inside the multiwalled carbon nanotubes were prepared using microwave plasma chemical vapor deposition (MPCVD) technique. The as prepared tubes were investigated by scanning electron microcopy (SEM), x-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). HRTEM study of these tubes exhibits long, good crystalline nickel filled CNTs with well-graphitized walls. Different orientations of filled metal with respect to graphitic walls have been observed and the orientations were found to get affected by the electron accelerating voltages of 200 KeV. We report that by deliberate e-irradiation at specific sites the crystalline planes of nickel can change their orientation. With continuous irradiation for 10-15 minutes the nickel starts evolving out of the tube. We propose that metal at the tip of the tube may be exposed by employing e-beam irradiation and it may be useful to study the true electrical properties of both the multiwalled carbon nanotubes and Ni nanorod inside the tube.