Phase diagrams binary system, limited miscibility

These qualitative assumptions are not contradictory to the results of solid-state solubility and phase diagram studies. According to these findings, the rare earth oxides are completely or largely miscible with UO2, whereas the alkaline earth oxides and zirconium oxide show a limited solubility and M0O2 is only soluble to a neglibly small extent (Kleykamp, 1985). However, results from studies performed on binary systems are not directly applicable to multi-component fuel - fission product oxide systems. In general, the maximum solubility of the individual fission product species in the fuel matrix will be reduced in the presence of additional constituents. 

When the overall composition is such that the system point falls in the area labeled P=2, two liquid phases are present. The compositions of these phases are given by the positions of the ends of a tie line through the system point. Four representative tie lines are included in the diagram, and these must be determined experimentally. The relative amounts of the two phases can be determined from the lever rule. In the limit of zero mole fraction of ethanol, the tie line falls along the horizontal base of the triangle and displays a miscibility gap for the binary system of benzene and water. (The conjugate phases are very nearly pure benzene and pure water). 

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