Abstract
Experimental results of an in situ study of displacement rates of growth steps, observed by optical microscopy, of different height on the {010} faces of potassium acid phthalate single crystals from aqueous solutions of predefined supersaturations up to 8.5% at about 30 °C are reported and discussed. It was found that: (1) there is a large spread in the displacement rate of steps even for the same supersaturation but the spread decreases with increasing value of supersaturation, (2) in some cases the step displacement rate decreases while in others it increases with increasing growth duration, (3) the average displacement rate of low‐height steps increases linearly with an increase in supersaturation, and (4) the velocity of steps decreases with an increase in their height. Analysis of the results showed that (1) the linear supersaturation dependence of step velocity occurs in the case of a supersaturation independent activation energy for growth, and (2) the supersaturation dependence of relative decrease in the velocity of steps with their height may be explained by three approaches: (i) net flux of growth units from the surface terrace to the advancing step, (ii) time dependent adsorption of solute molecules to the advancing step, and (iii) anisotropy in solute transport by surface diffusion to a step from the two terraces on its either sides (Schwoebel effect). In approaches (i) and (ii) the decrease in the step velocity is associated with the nucleation of kinks on step edges.