Dynamic Behavior of Nickel Atoms in Graphitic Networks

The dynamic behavior of nickel atoms in graphitic carbon onions, observed by in situ atomic-resolution electron microscopy, shows the formation of stable new C-Ni phases. Nickel is observed to take substitutional in-plane positions in graphene layers, forming a planar graphitelike C-Ni lattice. Evidence is furthermore seen for the formation of a cubic C-Ni phase, suggesting a possible phase transformation in C-Ni from a graphitelike to a diamondlike structure. The stability of the planar phases is shown by first-principles calculations which also indicate that the C-Ni planes are metallic.