A kinetic model of the transformation of a micropatterned amorphous precursor into a porous single crystal.

Biogenic single crystals with complex shapes are believed to be generated by the crystallization of an amorphous precursor. Recent biomimetic experiments on the crystallization of calcite via amorphous-to-crystalline transition point to the fact that the transformation kinetics may be controlled by the micropattern and the macroscopic shape of the amorphous precursor phase. Here we analyse a simple kinetic model, based on thermodynamic considerations, showing that the presence of cavities in the micropatterned precursor phase might interfere with the transformation process and control its kinetics. The size of the cavities couples to the total surface energy and, hence, to crystal nucleation and growth, while the spacing of the cavities, as compared to the typical diffusion path, controls the possible nucleation of competing crystals.