  Possible stably-ordered substitutional structures based on a graphene-type
crystal lattice are considered. A kinetic model of atomic ordering in
metal-doped graphene with stoichiometric (1/8, 1/4, 1/2) and nonstoichiometric
compositions is developed. Inasmuch as the intrasublattice and intersublattice
'interchange' ('mixing') energies are competitively different for
graphene-based lattice, kinetic curves of the long-range order (LRO) parameters
may be nonmonotonic for the structures described by two or three LRO
parameters.
