PROPAGATION OF SHORT-RANGE ORDER IN THE LATTICE-GAS

The lattice gas model is examined to make a comparison between the sup erposition approximation and one which is free from the approximation as long as the three-body distribution is concerned. The formulation i s applied to the type I superionic conductor, AgI, in which Ag-ions ca n move like the atoms in liquid and give rise to a strongly correlated Ag-ion distribution over available lattice sites. The oscillatory beh avior of the radial distribution function is found up to the seventh n eighbor distances including three maxima and three minima. The degree of disordered arrangement is then examined by calculating the latent h eat of transition from the ordered beta-phase to disordered alpha-phas e of the superionic conductor. (C) 1998 Elsevier Science B.V. All righ ts reserved.