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Liquid-(Solid plus Liquid) Transitions in a Two-Component System of (CH3)CCl3 + CCl4

Liquid-(solid + liquid) transitions are studied in (CH3)CCl3 + CCl4 by using the Landau phenomelogical model. The Gibbs energy is expanded in terms of the orientational disorder (OD) parameters for the transitions of the liquid-(rhombohedral + liquid) and liquid-(face-centered cubic + liquid) in a two component system of (CH3)CCl3 + CCl4. From the Gibbs energy, the phase line equations are derived for the transitions studied and they are fitted to the observed T-X phase diagram of (CH3)CCl3 + CCl4 for the concentration (X) CCl4. Temperature and concentration dependences of the OD parameters (psi and eta) and the inverse susceptibility (chi psi-1 and chi eta-1) for the two transitions of interest, are predicted by using the melting curves of (CH3)CCl3 + CCl4 on the basis of the Landau phenomenological model. Our predictions, which can be compared with the experimental data, indicate that the first order transition of the liquid-(solid + liquid), in particular, for (CH3)CCl3 + CCl4 can be described satisfactorily by the Landau mean field model.