Simple solution model

The most commonly used solution model to represent the liquid-phase behavior is the simple-solution model. Figure 18 shows a comparison between the recommended value of 0Alsb and the value calculated from the... 

To test the effect of using a solution model in the calculation of 0,j the simple-solution model was used in conjunction with either method I or method III to fit sets of data consisting of the liquidus temperature alone (146), liquidus temperature and enthalpy of mixing (147), liquidus temperature and activity (147), and all three types of data combined. With the parameters determined from the fit, values of 0 as a function of temperature were calculated and compared with the recommended value. 

Figure 19. 0 Aisbl as a function of reciprocal temperature. Values were calculated by the simple-solution model, with parameters estimated from a fit of the combined data set ( ), liquidus data only (—), liquidus and activity data...

Liquid-Solution Models. The simple-solution model has been used most extensively to describe the dependence of the excess integral molar Gibbs energy, Gxs, on temperature and composition in binary (142-144, 149-155), quasi binary (156-160), ternary (156, 160-174), and quaternary (175-181) compound-semiconductor phase diagram calculations. For a simple multicomponent system, the excess integral molar Gibbs energy of solution is expressed by... 

A number of attempts have been made to use the simple solution model to represent the solution nonidealities in binary (23,29-32) and ternary (23,33-41) III—V systems. In the simple solution model, the integral Gibbs excess energy is given in terms of an interaction energy a)( T) by the equation... 

The accuracy of thermodynamic simulation is dependent on thermodynamic model. It is quite easy to model the gas phase and the pure condense phases, while the liquid solution of oxide glasses have been difficult to model because of strong interactions between constituents, and it has been found that simple solution models do not accurately reproduce... 

Chapter 2 looks at the modeling and characterization of solid solutions. Following a quaUtative description of the different types of solid solution of substitution and insertion, the short-distance and long-distance order coefficients are introduced. Simple solution models are briefly described and the thermodynamics of the order/disorder transformations in alloys is presented. The chapter ends with the experimental determination of the activity coefficients of the components of a solid solution. 

The second chapter describes the tools used for macroscopic modeling of solutions. The use of limited expansions of the activity coefficient logarithm is presented, before we define simple solution models such as the ideal dilute solution, regular solutions and athermal solutions, on the basis of macroscopic properties. 

One of the simplest and most widely used models for the thermodynamic characterization of a nonideal solution is the so-called simple solution model . In this model the excess free energy of mixing, accounting for deviations from the ideal entropy of mixing, is taken as an expression that is proportional to the product of the mole fractions of the constituents. 

A plot of the LJ and WCA potentials is displayed in Figure 3. Simple solutions modeled with these solute-water potentials capture a wide range of hydrophobic behavior without the complications inherent in biochemical systems. 

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