Effect of DTPA on Rapid Growth and Performance of KDP Crystal

KDP crystals were grown by point seed rapid growth method in the presence of 1×10 −4 (mol/mol KDP) diethylene triamine penlaacetic acid (DTPA). Metastable zone width of the solutions with different saturation temperatures were extended by adding a small amount of DTPA. The influence of different concentrations of DTPA on the growth kinetics of (100) face of KDP crystal was studied by laser polarization interference technique. With the DTPA concentration increasing, the critical supersaturation (dead zone) was decreased continually, but the growth rate was firstly increased and then decreased, passing through a maximum. The UV-Vis transmission spectra and impurity content of main metal ions in the crystal were characterized as well. The results showed that the opti- cal transmittance in the UV region was enhanced significantly and the impurity content of main metal ions in the crystal was reduced effectively by the addition of 1×10 −4 (mol/mol) DTPA.