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Chapter II Solution Growth….
layer wise manner. The crystallizing substance is delivered to the step by
either bulk or surface diffusion. However, their relative role is not well
established.
Recently, many authors have discussed different crystal growth topics
covering mainly the solution growth, which are thermodynamics versus
kinetics [15], the terrace-step-kink approach and the capillary wave approach
to the fluctuation properties [38] and a comprehensive treatise on crystal
growth from solutions [39].
All methods of growing crystals from solutions are based on the
dependence of the solubility of a substance on the thermodynamic
parameters of the process, temperature, pressure and solvent concentration.
In the majority of the cases the temperature dependence of the solubility is
employed. The state of super-saturation is very essential for crystallization to
occur. One of the convenient ways in which the degree of super-saturation
can be expressed by the means of the following expression,
S = C /C *
Where, C is the concentration of the solution and C * is the equilibrium
saturation concentration at the same temperature. Hence different three
states of saturations are denoted by the values of S; namely, a saturated
solution indicates S = 1, under-saturated solution denotes S < 1, and
supersaturated solution indicates S > 1. Other common expressions of super-
saturation are the concentration driving force, Δ C, and relative super-
saturation, σ, defined by [40]
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