Agarose, gelatin, and silica gel media have been surveyed as appropriate matrices for the crystal growth of sodium bromate (NaBrO_3). Form pure aqueous solution, NaBrO_3 crystallizes with a characteristic tetrahedral habit. We have demonstrated that a greater variety of habits (e.g., cubic, tetrahedral, polyhedral, and dendritic) can be reliably obtained from the growth in these gel media by controlling the solute concentration and the gel density. Agarose and silica matrices suppress the nucleation as the gel density increases, while increasing gelatin concentrations seem to enhance crystal nucleation rates. These observations support the general hypothesis that the gel media influences the relative growth rates by controlling the solute nucleation and diffusion; however, little can be concluded about the possible chemical interaction between the polymer backbone and the solute.
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