Download (4Mb) - Etheses - Saurashtra University

Chapter II Solution Growth….
2.11 Inclusion
Inclusions are very important in crystal growth. The aim is always there
to grow inclusion free perfect crystal. Trapping of mother liquor into crystalline
imperfection is also a common problem in crystal growth, which results in loss
of stability by crystal growth form. In dendritic growth, parts of the mother
medium remains between the dendritic branches and communicate with the
bulk of the mother medium only through a network of narrow channels.
Inclusions are also trapped when the growth front as a whole remains
stable. In the case of this front is a singular face growing in layer wise
manner, the inclusions arise when growth takes place by deposition of
macroscopic rather than elementary steps. During the growth from solution,
the nutrition of the step rise is better in the vicinity of the outer edge than it is
in the vicinity of the inner edge forming the reentrant angle. The rise of macro-
step, therefore, cannot remain flat while propagating at high super-saturation
and a layer overhanging the growing face appears.
Macro-steps often have rounded shapes in the plane of the face along
which they propagate. In experiments the appearance of macro-steps, then
inclusions and finally ending into crystal cracking was noted [57]; Chernov [37]
has discussed inclusion of mother liquor and impurities at length.
2.12 Solution Growth Methods
A variety of crystals are grown by the solution growth techniques
for industrial applications. The size of the crystallizer vessels varies
depending upon the requirements, whether it is for the research or industry. A
82