Preparation of nickel-silver core-shell nanoparticles by liquid-phase reduction for use in conductive paste

Nickel-silver (Ni-Ag) core-shell nanoparticles (NPs) were prepared by depositing Ag on Ni nanocores using the liquid-phase reduction technique in aqueous solution, and their properties were characterised using various experimental techniques. The core-shell NPs had good crystallinity, and the thicknesses of the Ag nanoshells could be tuned effectively. The oxidation resistance of the Ag surface and the electroconductive properties of the Ni core allowed these Ni-Ag core-shell NPs to be used in a conductive paste. Thick films composed of Ni-Ag core-shell NPs were screen-printed on a polycrystalline silicon substrate then sintered at temperatures ranging from 500 degrees C to 800 degrees C. Stable resistivity was obtained when the sintering temperature was higher than 650 degrees C, and the electrical properties of the Ni-Ag core-shell paste were close to those of pure Ag paste. Thus, the Ni-Ag NPs can partly replace pure Ag NPs in conductive pastes.