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Chapter VII Reactivity at Dislocation….
Chapter VII
Reactivity at Dislocation in Pure and Amino acids Doped KDP
7.1 Introduction
Crystals
Reactivity of solids is of practical and fundamental importance. In some cases
like propellants, heterogeneous catalysis, etc., high reactivity is required;
whereas, the low reactivity is a need in oxidation and corrosion of materials. The
study of reactivity of crystals is mainly carried out by preferential etching and
gross dissolution. The preferential etching is subjected to the qualitative analysis
of the defects sites of a crystalline solid and, thereby, indicates the quality or
perfection of the crystal.
Etching though a simple and widely adopted technique for the study of
imperfections in a large variety of crystalline materials, the process is still not
very well understood. An etching technique in association with optical microscopy
can be used alternatively to X-ray method for the detection as well as quantitative
analysis of defects in crystalline solids [1-5]. The high-resolution imaging a
capability achievable with Atomic Force Microscopy (AFM), has enabled the
initial stages of the process of etch pit nucleation to be monitored on a scale
previously unattainable [6-7]. The segregation of foreign solute particles during
crystal growth leads to the introduction of defect into the crystals [8-9].
In the present study pure and amino acids (L-histidine, L-threonine and DL-
methionine) doped KDP crystals were subjected to chemical etching on their
(100) as grown faces. The kinetic as well as thermodynamic parameters are
reported in the present chapter for the motion of ledges of the etch pits.
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