Binary-phase diagram with eutectic formation

Fig. 1 Simple binary-phase diagram with eutectic formation. Ta is melting point of pure A Th is melting point of pure B and E is eutectic point.

The consequence of the above considerations is that binary systems of alkali metal halides form different types of phase diagrams, starting with the simple eutectic ones through the solid solution eutectic ones, the phase diagrams with the formation of a binary compound up to those with complete solid solubility. Tables 2.4 and 2.5 summarize the main features of individual phase diagrams. 

The change of halide ion results in weaker acidic properties for LnCl3 as compared with LnF3. This means that equilibrium (1.1.41) with the participation of alkali metal halide should be shifted to the left as compared with the fluoride complexes. That is, lithium chloride does not react with chlorides of the rare-earth elements with the formation of any compounds the binary phase diagrams are characterized by one simple eutectic. The same situation is observed for the binary diagrams for lithium- and rare-earth bromides. 

Figure 3.31. Phase diagram of the ternary eutectic system with the formation of the congruently melting binary...

The use of the differential thermal analysis in the phase diagram determination is illustrated in Figure 3.52. A hypothetical binary eutectic system A-B with the formation of the incongmently melting compound A4B was chosen. There are three thermograms (a) to (c) shown as examples. In thermogram (a), the first heat effect at temperature ai... 

The simple crystallization of a binary eutectic system only produces one of the components in pure form, while the residual mother hquor composition progresses towards that of the eutectic (section 4.3.1). There is often a need, however, to produce both components in pure form, and one way in which this may be achieved is to add a third component to the system which forms a compound with one of the binary components. Phase diagrams for systems with compound formation are discussed in section 4.3.2. 

Fig. 1-39. Phase diagram for a binary solvent/ dissolved substance system with eutectic point without solvate formation.

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