Atomic Force Microscopy Study of Self-Assembled Sodium Chloride Nanocrystallites and Their Morphology Transitions

Abstract

Identically oriented NaCl nanocrystallites have been grown on mica surfaces based on a facile solution-evaporated method. With an increase in humidity, the morphology of the NaCl nanocrystallites evolves in succession from triangular pyramids to cubic islands and then to long lines with lengths of up to millimeters. These nanocrystallites can self-assemble into highly ordered arrays with large spatial extents of ∼10 mm2 under high humidity conditions when the value of relative humidity is higher than 40%. Their morphology transitions and self-assemblies can be understood in terms of controlled epitaxial crystallization together with water adsorption at the surface of the growing nanocrystallites.