Morphology, evolution and other characteristics of gibbsite crystals grownfrom pure and impure aqueous sodium aluminate solutions

The effect of external conditions on the growth morphology of gibbsite, gam ma -Al(OH)(3), grown under a range of conditions has been studied. The resu lts show that during growth the morphology of gibbsite crystals evolves fro m thin, rounded hexagons and faceted lozenges into faceted plates and block s with well-formed basal, prismatic and chamfered faces. This morphology ev olution shows only a weak dependence on the growth conditions. Moreover, in creasing the driving force or the caustic concentration leads to larger cry stals, up to tens to a hundred pm in size. The influence of small amounts o f inorganic impurities on the growth of gibbsite crystals turns out to be n egligible. Different growth morphologies are obtained from potassium and ce sium hydroxide solutions. This indicates that the alkali ions of the soluti on have a major influence on the morphology of gibbsite. The twinning behav iour is similar for gibbsite crystals grown from sodium, potassium or cesiu m aluminate solutions. (C) 2001 Elsevier Science B.V. All rights reserved.