Crystallography, Cristallographie cristallogenèse, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure, proprietes mecaniques et thermiques, Condensed matter: structure, mechanical and thermal properties, Structure des liquides et des solides; cristallographie, Structure of solids and liquids; crystallography, Etat cristallin (incluant les mouvements moléculaires dans les solides), Crystalline state (including molecular motions in solids), Théorie de la structure cristalline, symétrie cristalline; calculs et modélisation, Theory of crystal structure, crystal symmetry; calculations and modeling, Calcite, Coalescence, Couche mince, Thin films, Dendrite, Dendrites, Démouillage, Dewetting, Etat surface, Surface states, Evaporation, Formation motif, Patterning, Gouttelette, Droplets, Mica, Solution aqueuse, Aqueous solutions, Symétrie cristalline, Crystal symmetry, Système complexe, Complex system, Sistema complejo, Verre, Glass, 6150A, NaCl, and Substrat plomb
We describe a method of generating remarkable crystal patterns on smooth surfaces such as mica, glass, or calcite. Very dilute droplets of aqueous salt solution (0.1 wt % NaCl) are deposited on the chosen substrate, and if the perimeter of these droplets becomes pinned by crystal deposition, they thin and concentrate by evaporation rather than shrink laterally. When thin enough, the liquid film ruptures by one of two mechanisms. In the first, crystals nucleate on the substrate and puncture the film, and as the holes grow radially from the rupturing crystal, the receding liquid rim deposits two-dimensional crystal dendrites. A second mechanism of rupture can occur with more dilute solutions (0.025 wt % NaCl), where attractive forces across the liquid film lead to rupture before crystals nucleate. This results in a pattern of bare patches surrounded by crystals, because supersaturation is only reached when the neighboring holes in the film are close to coalescence. The method is applicable to any solute in a volatile solvent on any smooth substrate, and the interplay of dewetting, crystal deposition, and symmetry of crystal and substrate leads to complex, system-specific patterns. The technique may be developed into methods of surface patterning with technologically important crystals.