Morphological evolution of silver crystals produced by reduction with ascorbic acid

Various kinds of unusual morphologies of silver crystals were obtained by reduction of AgNO₃ with L-ascorbic acid (AsA). Flower-like clusters having a hole at the center were produced with direct mixing of silver ions and the reducing agent. The outgrowth of petals composing the clusters was enhanced with increasing the [AsA]/[AgNO₃] molar ratio. The architecture of the clusters was drastically influenced with addition of acid or base into the reaction system. Especially, strange stringy clusters consisting of silver platelets were formed in the solutions containing a great amount of AsA anions with the presence of sodium hydroxide. The formation of these morphologies is ascribed to specific growth of silver crystal from a seed particle previously produced at a highly supersaturated condition with silver cations and AsA anions.