ORDERING EFFECTS ON THE INTERCALATION PROCESS WITHIN A STOCHASTIC LATTICE-GAS MODEL

We use the lattice gas model in a general mean field approach to inves tigate ordering effects on the dynamics of the diffusion process of in teracting mobile particles. Our study finds application in transitiona l compounds presenting a triangular structure. Consideration of the la ttice division into sublattices enables us to underline the appearance and the growth of finite size structure. The latter is quantified by inclusion of order parameters which represent the difference in the co ncentration of mobile particles composition of the overlapping sublatt ices. The calculations are based on solving the master equatios govern ing the time evolution of each sublattice average concentration. Numer ical results are presented first. Then, a Taylor expansion is consider ed to deal with analytical calculations. This allows to derive a simpl e expression of an effective diffusion coefficient in the limit of a q uasi-stationary approximation. The results show that the evolvement of the system towards its ordered state slows down the diffusion process of intercalated particles. The occurrence of long range order corresp onding to the commensurate structures is characterised by relative min ima in the representative curves of the diffusion coefficient.