A model for the composition dependence of sound velocity in liquid silver chalcogenides

It is known that superionic conductors such as silver chalcogenides exhibit an intermediate behavior between solids and liquids. This observation has lead to the concept of sublattice melting and to a model for superionic conductors such as a 'crystalline cage immersed in a viscous liquid'. On the other hand, it has been suggested that in the liquid phase of a superionic compound, there is a tendency towards sublattice ordering. In the present contribution, the two fluid model of superionic melt is presented. The model is applied to study the composition dependence of the sound velocity in liquid silver chalcogenides. It is shown that the model reproduces quite well the behavior observed experimentally. (C) 2002 Elsevier Science B.V. All rights reserved.