Typical Campbell Diagram

Figure 7-11. Typical Campbell diagram. (Courtesy of Elliott Company)...

Figure 7.43 Schematic diagram of a typical vapor phase epitaxy apparatus. Reprinted, by permission, from S. A. Campbell, The Science and Engineering of Microelectronic Fabrication, p. 341. Copyright 1996 by Oxford University Press.

When two or more solutes are dissolved in the solvent, it is sometimes possible to separate these into pure components or separate one and leave the other in solution. Whether or not this can be done depends upon the solubility and phase relations of the system under consideration. How to plot and use this data is explained by Fitch (1970), and Campbell and Smith (1951). It is helpful if one of the components has a much more rapid change in solubility with temperature than does the other. A typical example, which is practiced on a large scale, is the separation of KCI and NaCl from water solution. A simplified phase diagram for this system is shown in Figure 5.1. In this case, the solubility of NaCl is plotted on the Y-axis as parts per 100 parts of solvent, and the solubility of the KCI is plotted on the X-axis in the same units. The isotherms show a marked decrease in solubility for each component as the other component is increased. This example is typical for many inorganic salts. 

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