Control over the morphology of ceramic crystals by biomimetic processes is an important goal in contemporary materials engineering. While many parameters have been previously studied in such morphology control, the dimensionality of the crystallization template is one aspect that has not received much attention hitherto. In this paper, we examine the change in morphology of BaSO 4 crystals as they are grown on templates such as cysteine-modified colloidal gold particles (0-D), DNA (1-D), and within lipid bilayers stacks (2-D) at two significantly different supersaturation ratios. It is observed that large changes in the morphology of barite crystals occur, and tentative reasons are put forward to explain these changes.

In this paper we report on the growth of strontianite crystals at the interface between an aqueous solution of Sr 2+ ions and organic solutions of chloroform and hexane containing fatty acid/fatty amine molecules by reaction with sodium carbonate. When fatty acid was used as an additive at the interface, the crystals grown were self-assembled needle shaped strontianite crystallites branching out from the seed crystal via secondary nucleation. Under identical conditions of supersaturation, the presence of fatty amine molecules at the liquid-liquid interface resulted in needle shaped strontianite crystals with spherical crystallites arranged around central needles. This clearly indicates that the functionality of the head group of the amphiphiles at the liquid-liquid interface affects the morphology of the strontium carbonate crystals formed. The use of interfacial effects such as dielectric discontinuity, polarity and finite solubility of the two solvents etc opens up exciting possibilities for tailoring the morphology of crystals at the liquid-liquid interface and is currently not possible in the more popular crystal growth with similar amphiphiles at the air-water interface.

Barite crystals were grown at the interface between an aqueous solution of Ba 2z ions and organic solutions of chloroform and hexane containing fatty acid/fatty amine molecules by reaction with sodium sulfate. The crystals grown at the interface in all cases had a nearly similar flat, plate-like morphology consistent with the barite structure. This morphology of the crystals resembles that of barite obtained during growth in solution in the presence of crystal growth inhibitors and is significantly different from that of barite crystals grown at the air-water interface. The use of interfacial effects such as dielectric discontinuity, finite solubility of the two solvents, etc., opens up exciting possibilities for tailoring the morphology of crystals at the liquid-liquid interface.

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