ABSTRACT
The interfacial energy, g, however, varies as r2. For small embryo sizes, the free energy added to the system by the interfacial energy is therefore larger than the reduction in free energy provided by DGV. (Like g, W is always positive. As will be demonstrated later, W can be viewed as an algebraic additive under usual circumstances to DGV: therefore, W reduces the driving force for nucleation.)
The free energy of the embryo increases until the r3-dependent DGV can finally halt the rise in DG8, the total standard free energy change associated with the formation of an embryo, at a sufficiently large embryo size. This rise is halted when q(DG8)=qr¼ 0; the corresponding radius is termed, r*, the critical radius, or the radius of the critical nucleus size. At larger values of r, DG8 diminishes continuously and eventually becomes negative. Such behavior is shown graphically in Figure 2.1.
