Mechanism of Formation of CNTs
Major achievements
A link between the polymorphic form of an organometallic precursor, and the diameter and defects of the carbon nanotube product was identified. The polymorphic form of the precursor determines its sublimation temperature. When the sublimation temperature is below the decomposition temperatures of the precursor, vapours with fixed carbon-to-metal ratio are formed. This is a key finding in the CNT formation as pyrolysis of these vapours gives rise to CNTs with fewer defects and smaller diameters.
A method for simultaneous crystal size, crystal size distributions and micro-strain analysis en route to nanosized graphite by X-ray diffraction-line-profile analysis was reported by Milev et al. The analysis has the advantage of giving information about crystallite sizes over larger volumes and is sensitive to the strain fields of lattice defects, especially the different internal stresses related to dislocations. It is based on Fourier analysis of fitted Voigt functions to the graphite (002) and (004) X-ray reflections. This allows for determination of the size and strain Fourier coefficients from weak diffraction lines characteristic of nanocrystalline materials, where a direct Fourier analysis is not possible.
Band gap engineering utilising co-doping strategies.
Future plans and directions
Focus on the application of nanocarbons and other nanomaterials in the energy storage and energy transformation areas. Further investigation of the mechanism of carbon nanotube synthesis by manipulation of the supersaturation during the nucleation and growth stages.
Collaborator
Synthesis of catalysts for hydrocracking of biofuels from microalgae; (UWS-CSIRO project funded for 2 years)
Initiated collaboration with CSIRO Energy technology on nanocarbons for electric energy
storage application
Continuation of the Collaboration with Prof Isak Avramov from Institute of Physical Chemistry (IPC) at the Bulgarian Academy of Sciences on the mechanism of carbon nanotube formation (Milev visited in IPC July 2008). So far one paper is produced as a result of the collaboration
