  Here we demonstrate the selective bulk scale synthesis of delaminated
graphene sheets by a proper choice of magnetic field modulating an
electric-arc. An ultra-high purity glassy graphite anode was sublimated in an
argon atmosphere. Carbon nanotubes, as well as graphene sheets were found
inside the deposit formed on the cathode. Both the high purity carbon nanotubes
as well as graphene sheets, with minimal structural defects, were synthesized
separately by varying the strength and orientation of the external magnetic
field generated by arrays of permanent magnets. The as-synthesized carbonaceous
samples were characterized with the help of transmission electron microscopy,
selected area electron diffraction, Raman spectroscopy and thermogravimetry for
optimizing the highest selective production of delaminated graphenes. This
optimization was done by varying the strength and orientation of the external
magnetic field.
  The as-synthesized graphene sheets exhibited relatively high degree of
graphitization and low structural defect density as confirmed by RS. They were
found to exhibit higher oxidation temperature than that of the carbon
nanocrystalline particles as inferred from the thermogravimatric analysis.
Moreover, they were found to form scroll-like carbon nanotubes at their edges
on account of their surface energy minimization. This was confirmed by the
selected area electron diffraction analysis. With this new technique, we could
successfully synthesize delaminated graphenes at a rate of few grams per hour.
