Novel approach to study dispersion in growth and dissolution rate of crystals from solutions

Growth and dissolution rate dispersion of boric acid single crystal was investigated in supersaturated and undersaturated solution contained in a specially designed cell by in situ examination of crystals mounted at the tip of a needle, rotated between 0° and 360° and using an image analyzer system. Changes in the behavior of equivalent crystal diameters at different supersaturation and undersaturation and rotation angles were determined by using two new procedures: (1) rotating growing or dissolving crystals by 360° at intervals of 45° (Procedure 1: angular growth/dissolution rates), and scanning individual face at increments of 10° in the 360° range (Procedure 2: point growth/dissolution rates). It was found that: (1) dispersion in angular growth and dissolution rates is a general phenomenon due to different growth and dissolution rates of individual faces of a crystal, but this dispersion is reduced when the average growth and dissolution rates of all faces are taken into account, and (2) the point growth/dissolution rates of single crystal, calculated by procedure 2, are different from point to point.