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Chapter II Solution Growth….
From crystal chemistry point of view the growth units and forming
mechanism of KDP crystals is discussed by Weizhuo Zhong et al [81]. The
thickness of the boundary layers is changing with lattice faces as it has been
studied by the authors with Raman spectra, where the solution structure
during the crystal growth can be observed. It has been found that the solution
structure at the boundary layer is similar to that of the crystal, so that the
growth unit proposed as [H2PO4] - . The difference of growth rates of lattice
faces is determined by the combination of growth units, which is mainly
dominated by the angular orientation of K-O and H-O bonds. As a result, the
reason about the difference of growth rates of lattice faces and the influence
of pH values on the crystal morphology can be well elucidated.
In a quest to grow the long crystals of KDP, the Sankarnarayana –
Ramasamy (S-R) method has been employed by Balamurugan and
Balamurugan et al [82, 83]. A KDP crystal of 15 mm diameter and 65 mm
length has been reported. Furthermore, the feasibility of melt growth methods
for KDP crystals was checked by Pastor and Pastor [84]. Also, the gel grown
KDP [85] is reported.
The surface topography of KDP crystals has been studied by AFM
(Atomic Force Microscopy) by Yoreo et al [86]. Apart from this, Akasuma et al
[87] studied the topography characteristics of (100) and (101) faces of KDP
using AFM. Fractal dimensions of the surface patterns were measured by
them, including the step height and the terrace distance of KDP.
In the following section the growth of various amino acids (L - histidine
L- threonine and DL - methionine) doped KDP crystals will be discussed.
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