Synergistic Effect of Plasma and Laser Processes in Liquid for Alloyed-Nanoparticle Synthesis

Cu-Ag alloy nanoparticles (NPs) have been synthesized from micropowders of pure Cu and Ag using consecutively two non-equilibrium processes based on plasma and lasers in liquids. Plasma process reduces the size of initial micrometric powders down to nanometric size at which the laser fluence is sufficient to melt them, making alloying possible. Measurements at macroscopic (solution absorption), microscopic (scattering of individual NPs) and nanoscopic (electron microscopy) scales confirm alloying of NPs and homogenization in size and composition. This has noticeable effect on the final colloidal solution that absorbs yellow-orange light (550-600 nm) after laser treatment. The possibility to quench the as-formed liquid alloy leads to phase compositions that are not compliant with the phase diagram. With a synthesis rate of 360 mg/h, this process opens up interesting perspectives for non-equilibrium nanometallurgy of functional NPs.