Growth kinetics and surface morphology of crystals grown from solutions: Recent observations and their interpretations

Observations reported since 1980 on the kinetics of growth and surface morphology of crystals obtained from solutions are reviewed and interpreted from the standpoint of crystal growth theories. After a brief introduction to the theories of crystal growth, first the kinetics of growth are surveyed and confronted with the crystal growth theories. Here the origins of deviations in the linear dependences of inclination of growth hillocks and rate of displacement of their growth steps on supersaturation are analysed and explained in terms of kink nucleation at steps and solute accumulation at kinks. Thereafter the mechanisms of adsorption of impurities on growing crystal surfaces are briefly presented, and some typical experimental data on the kinetics of crystal growth in the presence of impurities and the tapering of KDP-type crystals are discussed in terms of the proposed mechanisms. The general features of growth hillocks at isolated and composite dislocation sources are then described and discussed in relation to the morphological importance of as-grown faces and growth conditions. The latest results on the bunching of elementary steps and the formation and stability of macrosteps are subsequently presented and discussed in the light of the existing theories of bunch formation. Finally, observations of dislocation hollow cores and decoration of growth steps on the as-grown surfaces of crystals during their extraction from supersaturated solution through an immiscible solvent layer placed above the solution are described.