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Chapter II Solution Growth….
growing by layer by layer mechanism [54, 55]. Moreover, the growth spiral
morphology on (100) KDP face related to impurity effect is analyzed on basis
of PBC theory by Noor and Dam [56].
The Bravais –Donnay- Harker Rule
According the Bravais rule, the minimum growth rates are
characteristic of the faces with the (h, k. l) orientation, that are parallel to
those atomic nets of the lattice between which the distance d h k i is the largest,
in other words, between which the bond strength is the least. As it is known
that d h k l α (h 2 + k 2 + l 2 ) -1/2, i.e., the largest d h k l corresponds to planes with
simplest indices, which often form crystal habit. The faces with simplest
indices are usually those of closest- packed atomic nets.
To find the growth shape one has to use the distance between the
nearest planes in which the atoms are situated, instead of d h k l. In determining
these distances, it is necessary to consider the space-symmetry elements in
the crystal structure. This is the modification suggested by Donnay and
Harker in Bravais rule. This has been discussed by Chernov [37] in detail.
Effect of Growth Conditions
The structure of the surface and the mechanism of growth depend on
super-saturation, temperature and composition of the environment, therefore,
the habit of the crystal depends not only on its structure but also on these
factors. For instance, at super-saturations of ≤ 1 % octahedron, cube,
rhombo-dodecahedron morphologies are obtained. The reason is that singular
faces have clearly defined non-linear dependence of the growth rate on the
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