Influence of additives on the crystal growth kinetics and growth rate of Ammonium dihydrogen phosphate (ADP) single crystals

Abstract

Metastable zone width (MSZW) of ammonium dihydrogen phosphate (ADP) solution was perpetrated by different concentration of additives like Borax, EDTA and Borax-EDTA admixture. The solubility, pH range and MSZW of ADP solution with a different combination of additives were determined and compared with pure system. On increasing the additive concentration, the supersaturation of ADP solution was found to increase. Nucleation time was calculated for different additive concentrations and compared to the pure ADP. It was observed that the increase in Borax concentration in ADP solution, stimulated faster growth along (100) and (010) direction. The additive concentration in ADP solution has shot up the total ionic strength. To decipher the critical nucleation parameters, induction-periods were analyzed and evaluated in accordance with the classical theory of homogeneous nucleation. The interfacial-energy values of ADP solution with additives were determined for different supersaturation ratio as a function of additive concentration. The different admixtures resulted in altered nucleation parameters such as radius of the critical nucleus and critical free-energy. Nucleation images of the ADP crystals were captured using in-situ nucleation cell.