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Chapter II Solution Growth….
In slow solvent evaporation method the super-saturation is achieved
by evaporating the solvent and as it evaporates the solute concentration
increases to above equilibrium value. The process is carried out at a constant
temperature under strictly isothermal conditions. Preferential evaporation of
the solvent occurs “spontaneously” if contact is provided between the solution
and the atmosphere, for non-toxic solvents. The rate of evaporation can
readily be controlled by changing the solution temperature or controlling the
passage using a screw-capped jar. The details of this technique are given by
Chernov [37].
2.12.1 Advantages of growth from solution
There are several advantages of crystal growth from solution. This
technique makes it possible to grow crystals that are unstable at their melting
points or those exist in several crystalline forms depending on the
temperature and provide control over temperature of growth [61]. Many times
an advantage in control of viscosity in solution growth methods which permits
crystals that tends to form glasses when cooled from their melts to be grown.
Low viscosity solvents such as water greatly accelerate diversification of silica
glass [44]. Generally, the rates of growth from melts are very large than those
from solution. Crystals grown from solution usually have well defined faces as
compared with those grown from melts. Solution growth methods are
comparatively inexpensive. In addition, the growth from solution can be
visually inspected; in fact it has been extensively used for studying the growth
parameters, including convection and transport, by means of photography.
However, the solution growth techniques are comparatively slower, requires
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