Phase diagrams binary isomorphous systems

AC or BC, which melts at a higher temperature than either of the pure elements (except for the InSb-Sb case). The binary phase diagram consists of two simple eutectic systems on either side of the compound (e.g., the A-AC and the AC-C systems). The third binary phase diagram represents solid-liquid equilibrium between elements from the same group. In Figure 1 the A-B portion of the ternary phase diagram is depicted as being isomorphous... 

We will now set out to compute the free energies for the solid and liquid phases of an ideal isomorphous binary system and the resulting phase diagram using a very simple model. If we add the entropy of mixing (Equation 12.3) to the dhemical potentials of pure A and pure B solid and we can write the free energy of the solid as... 

As mentioned earlier, texture observation cannot always be counted on to produce an unambiguous determination of the type of mesophase present. It can happen that similar textures are observed with two LC states separated by a phase transition. It is advisable, therefore, to use this method in conjunction with other types of characterization such as miscibility tests. Sackman and his school at Halle have produced a classification scheme for LMMLCs based on the criterion of complete miscibility of identical phases. " Isomorphous LCs are considered as equivalent and characterized by the same symbol. Therefore, the mesophases of a new compound can be positively identified by isomorphy with known mesophases of reference compounds. Assuming that the method is applicable to LCPs, the type of mesophase can be determined by establishing the isobaric temperature-composition phase diagram of a binary system composed of the polymer and a reference compound. Such diagrams can be generated from thermal data or, because of the various optical features characteristic of each mesophase... 

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