Silver nanoparticles: synthesis and size control by electron irradiation

Silver nanoparticles were synthesized by irradiating solutions, prepared by mixing AgNO3 and poly-vinyl alcohol (PVA), with 6 MeV electrons. The electron-irradiated solutions and the thin coatings cast from them were characterized using the ultraviolet–visible (UV–vis), x-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. During electron irradiation, the process of formation of the silver nanoparticles appeared to be initiated at an electron fluence of ∼2 × 1013 e cm−2. This was evidenced from the solution, which turned yellow and exhibited the characteristic plasmon absorption peak around 455 nm. Silver nanoparticles of different sizes in the range 60–10 nm, with a narrow size distribution, could be synthesized by varying the electron fluence from 2 × 1013 to 3 × 1015 e cm−2. Silver nanoparticles of sizes in the range 100–200 nm were also synthesized by irradiating an aqueous AgNO3 solution with 6 MeV electrons.