The role of hydrodynamics and supersaturation in the formation of liquid inclusions in KDP

Experimental study of polycrystal growth from an advecting supersaturated fluid in a model fracture

“…We can now discuss whether the microstructures in experiments presented here contain indicators for the flow direction and advective material transport. In single-crystal growth literature, it is described that there is an influence of the flow direction on the growth rate of facets located at the downstream side of crystals (Janssen-van Rosmalen & Bennema 1977;Prieto et al 1996). In natural systems, it was suggested that crystals grown by advective flow show a shape-preferred orientation (Newhouse 1941;Babel 2002).…”

Incidence of crystal growth conditions on the formation of macroscopic liquid inclusions in ciclopirox crystals

“…On the other hand, macroscopic defects can either consist of large alterations of crystal surfaces, of internal cracks, or result from the incorporation of a foreign phase inside a single particle (which should be distinguished from retention of matter caused by agglomeration). A few authors have reported the existence of gaseous vacuoles [14,15] but most of such defects are composed of liquid inclusions [16][17][18][19][20][21][22][23] (actually a saturated solution in the crystallization solvent). The solution is therefore trapped in the particle during crystal growth, resulting in detrimental consequences in terms of chemical purity, but also of chemical stability (risk of chemical degradation) and other solid state properties (compressibility, caking during storage, appearance of sticky material during grinding, etc.…”

Imaging techniques for mapping solution parameters, growth rate, and surface features during the growth of crystals from solution

“…134e139, 175e184] formation, perhaps by sweeping off bubbles or stagnant solution pockets. Finally, in the case of forced convection, Rosmalen et al have shown by wind-tunnel modeling that inclusions can occur in regions where stagnant eddies are likely to occur [428]. In summary, inclusions appear to be formed by several mechanisms, including localized interface instability, converging or intersecting growth layers, or the occlusion of a stagnating solution pocket by lateral overgrowth; therefore, they have a complex relation to convection.…”

“…The usual method for determining the saturation temperature of a solution or for establishing the initiation of growth is to determine, by shadowgraph or schlieren imaging, whether the convection is ascending or descending from a seed crystal [198,458]. Moreover, since the formation of fluid inclusions has been directly related to the convection pattern around a crystal [62,69,71,428], the growth of large inclusion-free crystals often depends upon the optimization of forced convection patterns by visualizing or modeling the convection [428]. Even when convection is substantially absent, as in microscopic or microgravity experiments, it must be monitored since even low-level residual or transient convection can have a significant effect on crystal perfection [350].…”