Dual action of Impurities in Crystal Growth from Solutions

A dual action of impurities becomes evidently in growth kinetic of prismatic faces of KDP. At higher supersaturation two‐dimensional nucleation mechanism due to impurities prevails. At smaller supersaturation the blocking effect of the steps created by the dislocation mechanism of growth become efficient. The limit of the “dead” growth zone depending on the impurity's concentration and the solution pH is a result of this last effect and agrees with the Cabrera‐Vermilyea mechanism.