Optical Properties of Ag-Cu Alloy Nanoparticles Synthesized by DC Arc Discharge in Liquid

Abstract

Alloy nanoparticles are much interesting because their properties are flexible and can be very distinct with the particles of their constituents. Optical properties of alloy nanoparticles can differ by size effects and composition of their pure components. The aim of this article is studying the alloying and optical properties of Cu-Ag nanoparticles prepared via DC arc discharge in water with two different experimental procedures. Arc discharge was ignited between two pure silver and copper electrodes and two types of sample productions were held. The first one was based on using copper and silver wire with 99.99% purity as an anode and cathode electrodes and at the same 3mm diameter in each part by two different 40, 50 A current. Second one was using reversed sited electrodes. Optical properties, size and crystal structure of nanoparticles were characterized by UV-visible spectroscopy, Field Emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) respectively. SEM images show the nanoparticles are spherical with the average size of lower than 30nm for all samples. XRD results shows there are some displacements in Bragg diffraction angles of silver XRD peaks which is due to the positioning of Cu atoms among silver atoms and synthesis of Ag-Cu alloy nanoparticles. However some Ag-Cu alloy peaks were also observed. In comparison with the optical extinctions of pure copper and silver nanoparticles the optical extinctions of samples have the characteristic optical extinction of Ag-Cu alloy nanoparticles with extinction peak due to surface plasmon resonance that was observed between silver and copper nanoparticles extinction peaks. In addition optical properties of Ag-Cu alloy are more adjustable with arc current when using copper and silver wire as anode and cathode electrode respectively. The results provide a simple and flexible method for preparation and tuning optical properties of Ag-Cu nanoparticles.