Binary system, without solid solution

Binary Systems without Solid Solution Eutectic Systems... 

Figure 5.18. Ti, Zr, Hf binary alloys. Dashed boxes show selected metals which, at least at high temperature, form one field (and in some cases two, a and (3, fields) of continuous solid solutions with the 4th group metals. Notice that these metals are in a small region of the Periodic Table close to the 4th group. In the systems marked by an asterisk intermediate compounds are formed (with or without a continuous solid solution).

Solid-Solution Mixture In this system, a binary mixture is cooled but neither component solidihes without containing some of the other component Both components are deposited simultaneously, and the deposited sohd phase is a solid-solution. Only two phases can exist in such a system a homogeneous liquid-solution and a solid-solution. The equilibrium phase diagram is shown in... 

The binary phase diagram for MgO-Al203 is simpler than that for the Ca0-Al203 system (Fig. 2). There is only one stable intermediate compound that of the spinel phase (Mg2A104) [60]. Spinel melts at 2,105°C, but there is a eutectic at 1,995°C and a limited solid solution between stoichiometric spinel and MgO (periclase), up to 6wt% MgO, can be dissolved into the spinel structure without exsolution. This limited solid solution is an important property that is utilized in manufacture of spinels for use in reducing conditions [70]. 

Liquid Solution Behavior. The component activity coefficients in the liquid phase can be addressed separately from those in the solid solution by direct experimental determination or by analysis of the binary limits, since y p = 1. Because of the large amount of experimental effort required to study a ternary composition field and the high vapor pressures encountered in the arsenide and phosphide melts, a direct experimental determination of ternary activity coefficients has been reported only for the Ga-In-Sb system (26). Typically, the available binary liquidus data have been used to fix the adjustable parameters in a solution model with 0,p determined by Equation 7. The solution model expression for the activity coefficient has been used not only to represent the component activities along the liquidus curve, but also the stoichiometric liquid activities needed in Equation 7. The ternary melt solution behavior is then obtained by extending the binary models to describe a ternary mixture without additional adjustable parameters. In general, interactions between atoms in different groups exhibit negative deviations from ideal behavior... 

Systems of type la (without critical phenomena in solid saturated solutions) (Figure 1.14). This is the simplest type of binary system. Most of the divariant (L-G, L-Sa, L-Sb, G-Sa, G-Sb) and monovariant equilibria (L-G-Sa, L-G-Sb, L = G) in the binary system (A-B) are the monovariant and nonvariant, respectively, with equilibria of one-component subsystems (A and B), spreading into two-component region of composition. Only the phase equilibria with two solid phases (invariant eutectic equihbrium (L-G-Sa-Sb) monovariant equilibria (L-Sa-Sb, G-Sa-Sb) and divariant equi-lihrium (Sa-Sb)) appear in the binary mixture as a result of an interaction of phase equilibria that extend fi om one-component subsystems. 

The present chapter does not pretend to be an exhaustive record of Solid-Liquid calorimetry applications in Surface Science and Technology. It should be rather regarded as an introductory course with some illustrative examples. It is important to realise that the individual author s experience in the field has been the principal criterion for selection of specific instruments and their uses, without any intention of neglecting other contributions. The presentation of calorimetry methods will be restricted only to interfacial systems composed of a pure liquid or a dilute binary, at the most, solution in contact with a solid which does not dissolve in the liquid phase. This formalism may be still employed in the case of solutions which are not strictly binary but may be viewed as such (e.g., solutions containing ionizable solutes, background electrolytes or other additives that may be lumped together as constituting a mean solvent or a mean solute). 

Angelopoulos et al. [42] reported that A -methylpyrroli-dione (NMP) could dissolve PANI in the base form. Subsequent work demonstrated that PANI solutions formed in NMP at solids concentrations above 6% formed gels after a short period of time [43-45]. The formation of these gels at concentrations necessary for the formation of fibers and films by solution spinning technologies (>10%) prohibited the use of this solvent without modification to a binary solvent system. 

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