Raman scattering investigation of the effect of EDTA additives on growth habit of KDP

KDP crystal is grown from solutions in the presence of doping Ethylenediamine tetra acetic acid (EDTA) in the concentration range of 0-500 ppm, and the growth rates of prismatic and pyramidal faces of KDP crystal are measured, respectively. The Raman spectrums of crystal growth solution in different growth layers with and without EDTA are investigated. Experiment results show that the macroscopic growth habit of KDP crystal will change obviously by adding a small quantity of EDTA into the growth solution. For the prismatic faces, it has been found that additive EDTA is favorable to the formation of growth units and thus it can enhance the crystal growth rate. For the pyramidal faces, EDTA additive also has an enhancing effect on the growth rate, but this effect is not considerable compared to prismatic faces. Our research results also show that EDTA does not affect the crystalline quality. (C) 2001 Elsevier Science B.V. All rights reserved.