influence of different percentages of copper on the size and optical properties of ag-cu nanoparticles formed by wet-chemical method

in this work, ag-cu nanoparticles (with different percentages of copper, 10%, 25%, 50%, 75% cu) were synthesized by wet chemical method. copper(ii) sulfate and silver nitrate were taken as metal precursors, ascorbic acid as reducing agent and anhydride maleic (ma) as a modifier. the prepared nanoparticles were characterized by means of x-ray diffraction (xrd) technique and scanning electron microscopy (sem-edax), fourier transform infrared spectroscopy (ft-ir) and uv-vis spectroscopy. sem indicated the formation of uniform spherical crystalline nanoparticle in a well distributed size and morphology. it can be seen from these pictures that the particle size decreased with increasing of the copper percent. when the molar ratio of cu2+/ag+ is 75/25 (>50%), mixture of the spherical and hexagonal nanoparticles was prepared. three pronounced ag diffraction peaks (111), (200) and (220) appeared at 2θ = 38°, 43.9° and 64.1°, respectively. the three most intense peaks of the xrd pattern of sample showed a slight shifting of the center of the diffraction peaks toward a lower angle. no shifting was observed in xrd lines with the increase of cu2+ to ag+ ratio in the cu2+/ag+ mixed solution (> 50% cu). fourier transform infrared spectroscopy (ft-ir) showed that nanoparticles are coordination between oxygen atoms and nanoparticles, because functional unit c=o present in ma, shifts to 1652.69 cm-1 after embedding nanoparticles. the position of the surface plasmon resonance (spr) absorption band on the nanoparticles could be shifted from 380-350 nm via the change of their percentage of cu.