Phase diagram, binary melting

Solubility of racemic praziquantel was determined in MeOH and 2-PrOH in the temperature range between 0 °C and 40 °C. A ternary phase diagram of praziquantel enantiomers and the MeOH system was also determined (06CH259). The solubility phase and binary melting-point phase diagrams were determined. Experimental and predicted aqueous solubility of praziquantel was reported (07CPB669,08SQE191). Dissolution of praziquantel... 

Alloys. Many Ge alloys have been prepared and studied. Most have been made by melting Ge with another metal, much as germanides are made. Collections of binary phase diagrams and comments about many Ge alloys are available (25—28). 

The distribution-coefficient concept is commonly applied to fractional solidification of eutectic systems in the ultrapure portion of the phase diagram. If the quantity of impurity entrapped in the solid phase for whatever reason is proportional to that contained in the melt, then assumption of a constant k is valid. It should be noted that the theoretical yield of a component exhibiting binary eutectic behavior is fixed by the feed composition and position of the eutectic. Also, in contrast to the case of a solid solution, only one component can be obtained in a pure form. 

Binary phase diagrams indicate that the rare-earth dodecaborides do not melt congruently . Owing to the difficulty in preparation of single-phase and single-crystal dodecaborides, little information is available on their physical properties. 

When two metals A and B are melted together and the liquid mixture is then slowly cooled, different equilibrium phases appear as a function of composition and temperature. These equilibrium phases are summarized in a condensed phase diagram. The solid region of a binary phase diagram usually contains one or more intermediate phases, in addition to terminal solid solutions. In solid solutions, the solute atoms may occupy random substitution positions in the host lattice, preserving the crystal structure of the host. Interstitial soHd solutions also exist wherein the significantly smaller atoms occupy interstitial sites... 

Differential. thermal analysis can also be used to construct binary phase diagrams on the basis of observed melting points. This information is of importance since the nature of the phase diagram as would exist for an enantiomeric pair can be instrumental in choosing a resolution strategy [23,24]. When a drug candidate contains one or more chiral centers, it is frequently... 

Figure 4.10 (a)-(i) Phase diagrams of the hypothetical binary system A-B consisting of regular solid and liquid solution phases for selected combinations of Q q and Qs°l. The entropy of fusion of compounds A and B is 10 J K 1 mol-l while the melting temperatures are 800 and 1000 K. 

Figure 2.1. Examples of melting phase diagrams of binary systems showing complete mutual solubility in the solid and in the liquid states (L liquid field, S solid field). The melting behaviour of the Mo-V, Cs-Rb and Ca-Sr alloys is presented. Notice the different ranges of temperature involved. The melting points of the pure metal components are shown on the corresponding vertical axes. The Cs-Rb is an example of a system showing a minimum in the melting temperature. In the Sr-Ca system complete mutual solid solubility is shown in both the allotropic forms a and (3 of the two metals.

Figure 2.9. Examples of melting phase diagrams of binary systems showing complete mutual solubility in the liquid state and, at high temperature only, in the solid state. By lowering the temperature, however, the continuous solid solution decomposes into two phases. In (d) a schematic representation of NiAu or PtAu type diagrams is shown as formed by two generic components A and B.

Figure 2.18. Examples of binary phase diagrams in each of which one stoichiometric phase is formed. In the Mg-Ge system we have the congruently melting Mg2Ge (33.3 at.% Ge) in Au-Sb, AuSb2 is formed through a peritectic reaction. In the Pt-Ag system one compound at 47 at.%...

Figure 3.50. The Yb-Cd binary phase diagram. The congruently melting compound YbCd57 is the first stable binary quasicrystal identified.

A melt is a liquid or a liquid mixture at a temperature near its freezing point and melt crystallisation is the process of separating the components of a liquid mixture by cooling until crystallised solid is deposited from the liquid phase. Where the crystallisation process is used to separate, or partially separate, the components, the composition of the crystallised solid will differ from that of the liquid mixture from which it is deposited. The ease or difficulty of separating one component from a multi-component mixture by crystallisation may be represented by a phase diagram as shown in Figures 15.4 and 15.5, both of which depict binary systems — the former depicts a eutectic, and the latter a continuous series of solid solutions. These two systems behave quite differently on freezing since a eutectic system can deposit a pure component, whereas a solid solution can only deposit a mixture of components. 

Finally, the high-temperature peak at 452°C in Fig. 3.14 is due to the eutectic melting of the AljMg and Al(Mg) mixture according to the binary Mg-Al phase diagram [122]. 

If the diffusion of a minor or trace element can be treated as effective binary (not uphill diffusion profiles) with a constant effective binary diffusivity, the concentration profile may be solved as follows. The growth rate u is determined by the major component to be n D ff, and is given, not to be solved. Use i to denote the trace element. Hence, w, and Dt are the concentration and diffusivity of the trace element. Note that Di for trace element i is not necessarily the same as D for the major component. The interface-melt concentration is not fixed by an equilibrium phase diagram, but is to be determined by partitioning and diffusion. Hence, the boundary condition is the mass balance condition. If the boundary condition is written as w x=o = Wifl, the value of Wi must be found using the mass balance condition. In the interface-fixed reference frame, the diffusion problem can be written as... 

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