3k3T3ln S2

ferent expressions for A and this can cause considerable differences in the attained values of J (Mersmann, 1995; Sohnel and Garside, 1992; Kashchiev, 2000).

Heterogeneous primary nucleation The occurrence of homogeneous nucleation is rare, in practice since nucleation on a foreign substrate will substantially reduce the nucleation barrier. For this type of nuclea-tion, a similar rate equation can be used:

Jhetero AheteroS exp

16^y3Vmolar 3k3T3(ln S)2

where the interfacial tension y is replaced by a much lower yeff. Although Ahetero is lower than A, the effect of the exponential term dominates up to very high supersaturation values, that are rarely met in practice (Figure 4).

Secondary nucleation The classic expression for the secondary nucleation rate in a suspension of growing crystals, B0, is the empirical power law, based on three experimentally accessible parameters that were recognized already early on to be important:

Solar Panel Basics

Solar Panel Basics

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