  The deconfinement phase transition is studied in the FL model at finite
temperature and chemical potential. At MFT approximation, the phase transition
can only be the first order in the whole $\mu-T$ phase plane. By a Landau
expansion we further study the phase transition order and the possible phase
diagram of deconfinement. We discuss the possibilities of second order phase
transitions in FL model. By our analysis the cubic term in the Landau expansion
could be cancelled by the high order fluctuations. By an ansatz of the Landau
parameters, we obtain the possible phase diagram with both first and second
order phase transition including the tricritical point which is similar to that
of the chiral phase transition.
