# “Formation and spreading”

The number of nuclei appearing per unit of surface is:

The progression rate of the steps is:

Hence, the growth rate:

Example 2.5.-

Note that if AG2 is nullified, that is, if the linear energy у* _{t}* is nullified, growth becomes:

Growth becomes of the same order as that of a K face and is consequently limited for the transfer through the diffusion layer.

# Diffusion-integration combination

According to results obtained previously, the growth rate’s integration mechanisms are announced by the following equations:

Formation and spreading R, = D c^{5/6} exp (B / 3LnS)

Spiral dislocations R, = Ec^{2}th (Cj / a)

All of these functions increase monotonically according to the relative supersaturation a. They are zero for c = 0 .

The molar flow density crossing the diffusion layer is:

This corresponds to a growth rate of:

c*: solution concentration at equilibrium (kmol.m^{-3})

П : molecular volume (m^{3}.kmol^{-j}).

In addition, we can write out:

c_{0} is the concentration at the interface separating the diffusion layer and the integration layer.

The calculation of a, is performed by equating rate R, (a,) for integration and rate R_{D} (a_{D}) for diffusion.

An analytical solution is possible in both extremes of the dislocation mechanism (oi << о and Oi >> a).

The “formation and spreading” mechanism is not susceptible to a numerical resolution.