Effect of organic impurities on the surface morphology and growth mechanism of KBP crystals (C8H5O4K)

The surface morphology of the (010) face of potassium biphthalate (KBP) cry stals grown from aqueous solutions under the supersaturation ranging within 0.029-0.04 has been studied by the methods of optical and electron microsc opies. It was revealed that the (010) surface has polygonal growth macrohil ls of the dislocation nature, small hillocks developing by the mechanism of successive two-dimensional nucleation, and numerous two-dimensional nuclei . The density of small hillocks ( 10(4)-10(5) cm(-2)) exceeds the dislocati on density in KBP crystals by one to two orders of magnitude. It is shown t hat at low supersaturations, the (010) face grows simultaneously by the dis location mechanism and the mechanism of successive two-dimensional nucleati on. It is also established that the tangential velocity of growth-step moti on on the (010) face increases in the presence of organic impurities. This effect can be used as one of the factors increasing the growth rates of cry stal fates at low impurity concentrations (the so-called catalytic effect o f impurities). (C) 2001 MAIK "Nauka/Interperiodica".