Phase formation and stability of Ag–60 at%Cu alloy nanoparticles synthesized by chemical routes in aqueous media

Abstract

The present work reports the nature of the evolution of an array of nanoparticles during the synthesis of alloy nanoparticles of Ag–60 at%Cu by the co-reduction of metal salt precursors using NaBH₄ in an aqueous medium. This was achieved by studying samples extracted at different intervals of time from the reaction bath. The microstructural characterization reveals that at the initial stage of synthesis, a single-phase solid solution of alloy nanoparticles of very small sizes was formed; however, as the reaction time increases, a network of chains of nanoparticles evolves containing particles rich in either Ag or Cu. Keeping the particles in the reaction bath for a longer time, the chemistry of the network changes further with the chain containing an Ag-rich core and Cu₂O as the shell. In the present study, we tried to rationalize the evolution of the phases from the observed results.