Modelling the crystal growth rate of KDP in the presence of organic admixtures

The crystal growth rate model in multi-component solutions was proposed on the basis of a two-step growth model, which employs the Maxwell-Stefan (MS) equations in the diffusion layer and a surface-reaction model of crystal growth, i.e. Burton, Cabrera, and Frank (BCF) surface diffusion and birth and spread (B+S) model, in the surface-integration layer, respectively. The model was applied to the growth of potassium dihydrogen phosphate (KDP) crystals in the ternary KDP-water-admixture (urea, ethanol and 1-propanol) systems. The model parameters were estimated using the experimental growth rate data. It was shown that the proposed model determines the growth rate and the interface concentration of each component successfully. Furthermore, surface analysis on the KDP (101) face growing from pure and admixture solutions was performed using ex situ atomic force microscopy (AFM).