This subcooling was sufficient to promote growth and minimize nucleation.
The bulk supersaturation (σ = 0.07) was generated by cooling down a saturated solution of boric acid at 25 ☌ in a thermostatic vessel. Scans were acquired every 64 s, and the scanned area was 20 × 20 μm 2. To perform the measurement for the next concentration, a fresh solution was pumped through the cell at 0.85 mL/min.
The cell was filled by pumping the saturated solution through it at 0.85 mL/min after that, the flow rate was changed to 0.07 mL/min during growth. Moreover, this information is of significance for the improvement of the quality of boric acid recovered from brines and minerals and the synthesis of nanostructures and microstructures of boron-based materials.įor each experiment, one single crystal of boric acid was glued on a glass slide, using two parts glue to expose the (001) face, and put it inside the flow cell. The adsorption of the salts on the crystal surface is anisotropic and independent of the supersaturation and preferentially on the active sites of the (100) edge. The reduction of the relative growth rate could be explained by the inhibition of advancement of steps of the (001) face mainly in the growth direction caused by the adsorption of salts on the actives sites and the inhibition of the formation of sources of steps such as dislocations. The results show that the growth mechanism of boric acid from its pure and impure solutions is spiral growth driven by screw dislocation and that the velocity of advancement of steps on the crystal surface, and the relative growth rate (ratio of the growth rate in presence and absence of a salt) is reduced in the presence of salts. For this purpose, atomic force microscopy in situ has been used. The crystal growth of boric acid from an aqueous solution in the absence and presence of sodium and lithium sulfate was studied by real-time monitoring.
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