Crystals additive inhibited growth

In this case at least, the fluidized bed system showed considerably faster growth rate kinetics than the stirred tank system, presumably by convective enhancement in the boundary layer on the surface of the crystals. Additionally, since nucleation suppressants nearly always also inhibit the growth rate, the slower growth kinetics in this case are not unexpected. 

Once this mechanism was established, it became possible to exploit it in order to systematically modify the morphology of crystals by tailoring additives which bind at a preselected face and thus inhibit growth in a predictable manner. 

FIGURE 17.2 The control of crystal morphology by controlling the crystal face growth rates. If additives are adsorbed on a face that inhibit growth, the final surface of the crystal will be dominated by the slowest growing crystal face. 

There have been many instances of examination of the effect of additive product on the initiation of nucleation and growth processes. In early work on the dehydration of crystalline hydrates, reaction was initiated on all surfaces by rubbing with the anhydrous material [400]. An interesting application of the opposite effect was used by Franklin and Flanagan [62] to inhibit reaction at selected crystal faces of uranyl nitrate hexa-hydrate by coating with an impermeable material. In other reactions, the product does not so readily interact with reactant surfaces, e.g. nickel metal (having oxidized boundaries) does not detectably catalyze the decomposition of nickel formate [222],... 

---