Composition and structure of NiAu nanoparticles formed by laser ablation of Ni target in Au colloidal solution

Abstract

Bimetallic NiAu and complex NiO:Au nanoparticles were formed by laser ablation of Ni target immersed in the colloidal gold solution. Effect of laser parameters (pulse duration, fluences and ablation times) on size and composition of nanoparticles was investigated by ablating the target with two Nd:YAG lasers at 1064 nm, operating with different pulse durations, 150 ps and 20 ns. Stronger ablation of the Ni target and subsequient synthesis of nanoparticles is achieved with picosecond pulses, compared to the nanoparticles production with nanosecond pulses, because the former ablation induces activation of different reactions between species in the colloidal solution. Shape, size and composition of the synthesized nanopraticles were found to correlate with the concentration of Ni species in the colloidal solution. Higher Ni concentration leads to formation of larger NiAu nanoparticles in form of solid solution. Smaller nanoparticles with lower Ni concentration in the colloidal solution were achieved by their synthesis during nanosecond pulses, when the obtained distribution of composition corresponds to the NiO matrix with incorporated golden nanoparticles. The results also demonstrate that the formation of bimetallic NiAu and complex NiO:Au nanoparticles were possible by means of laser ablation in liquids.