Search

Experimental data on the morphology of KCl microcrystals are interpreted from estimations of the possibility of growth of the (100) and (111)2faces. Ion attachment energy and water adsorption energy for five different growth sites on the (100) face were calculated for different solution concentrations c and temperature T = 298.15 K using the molecular interaction model of cluster formation applied to large cubic KCl clusters with specified growth site in the centre of one of the (100) face. The results show that, above the equilibrium concentration c0= 4.17 mol/dm3, attachment of ions is possible only for dislocation originated kink sites where the ion attachment energy is positive. For c > 5.3 mol/dm3, ions can also join a step producing new kink sites, thus increasing the growth velocity of (100) face. Further increase in the growth velocity is predicted to occur in solutions with c > 5.7 mol/dm3when formation of growth islands is possible.

The available experimental data on the supersaturation dependence of induction period for the nucleation of some compounds crystallizing from solutions are analysed from the standpoint of the classical nucleation theory and the mononuclear and polynuclear models in order to obtain values of interfacial tension and pre‐exponential factor for homogeneous and heterogeneous nucleation. It was found that the contributions of homogeneous and heterogeneous nucleations to the experimental data can be separated by assuming that the nucleation rates due to the two nucleations are additive and that the polynuclear model in combination with the separated contribution of homogeneous nucleation to the induction period gives a satisfactory agreement between theoretical estimates and experimental values of the interfacial tension and the pre‐exponential factor.

Several letters to the editor about the role of formal program verification, a calendar computation program, and operations research are presented.