Silver carboxylate nanostructure nucleation and growth on AgBr crystals

Abstract

The initial stage of the reaction between sodium stearate (NaSt) andAgNO3 produces silver stearate(AgSt) micelles, [(C18H35O2)x(Nax−y)(Agy)(H2O)z], and aggregations of these AgSt micelles in the form of cubic pre-AgSt crystals.When cubic grains of 50 nm AgBr are added to the NaSt dispersion prior to theAgNO3, the reaction proceeds to form the silver stearate micelles, but not the aggregation of thosemicelles. Instead, the {111} silver ion planes of the cubic AgBr crystal corners providenucleation sites for silver stearate micelle deposition and crystal growth. After nucleation,the AgSt micelles evolve into nanostructured bud-like formations via an epitaxial interfaceon one or several corners of each AgBr cubic crystal. Over time, additional AgSt micelledeposition enables the buds to grow longer into strand-like structures, whichthen connect to form the beginnings of the ultimate silver stearate crystal plates.