Incongruently. melting compound

Some compounds do not have a sharp melting temperature, but rather decompose on heating into a liquid and another solid below the liquidus temperature. When the compound AmB is heated, it decomposes into solid A and liquid of p at die temperature 7>. The compound A B is stable only up to the temperature 7>. This type of compounds is called an incongruently-melting compound. 

In the previous diagrams, points e and / for the congruently-melting compound are both ternary eutectic. On the other hand, for the incongruently-melting compound die point e is the ternary eutectic, whereas the point/is the ternary peritectic. 

Fig. 11.7. Isobaric phase diagram of a binary system where the following reaction takes place A + B — C resulting in (a) a congruent melting compound and (b) an incongruent melting compound.

Figure 11.14. Metastable extensions of equilibrium-phase boundaries. Solvus line extensions usually form a liquid miscibility dome. Extensions of incongruently melting compounds form a congruent melting point and extensions of congruently melting compounds often form eutectics with non-neighboring phases.

The phase diagram of the ternary system with the formation of an incongruently melting compound has four planes. Planes pc(A), pc(B), pc(C), and pc(A4B) are the projections of the planes of primary crystallization of the compounds A, B, C, and A4B, respectively. The figurative point of the binary compound A4B lies in the boundary of the binary... 

Figure 3.41. Phase diagram of the quaternary reciprocal system A" ", B+, C + // X, Y with the formation of two congruently and one incongruently melting compound.

The BioHi4-bcnzene system is a simple eutectic (eutectic point 20mol% Bi()Hi4, -7.0 °C). In BioH 14-toluene an incongruently melting compound is formed. Another group of workers have reported equilibrium diagrams for the Bi()H]4-arene systems (arene = benzene, durene, naphthalene, or biphenyl). ... 

The sodium sulfate-water system forms an incongruently melting compound, Na2S04 IOH2O (Fig. 15.15a). The line eb is the solubility curve for the decahydrate, while the line ba is the solubility curve for the anhydrous salt. The figure shows that the solubility of the decahydrate increases, while that of the anhydrous salt decreases with... 

There is some question as to whether material of the composition InClz is a compound melting sharply at 235°, an incongruently melting compound, or indeed a true compound at all. ... 

Incongruently melting compounds were noted for CaFsH + and... 

The incongruent melting compound 2KC1.3NbCl5 was reported to form between 413 K... 

After our experimental work with DTA and X-ray diffraction method, it is indeed proved the existence of an incongruent melting compound (Cs2CaF4). The phase diagram revised by us is shown in Fig. 6.2b [47]. 

Author Bukhanova,G.A. No solid solution,but has two incongruently melting compounds. Author Bergman,A.G. 

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