Radiation-Induced Synthesis and Characterization of Copper and Chromium Nanoparticles

Many of researchers nowadays synthesize Cu and Cr nanoparticles using chemical and electrochemical method which contribute to the complicated synthesizing process and reduction of metal ions cannot be carried out without using reducing agent. Gamma irradiation method was successfully applied to the preparation of Cu and Cr nanoparticles embedded in PVA and PVP polymer matrix in aqueous solution under ambient temperature. The aqueous solution of CuCl2 and CrCl3 blend in both polymer matrixes were irradiated with 60Co gamma rays to doses up to 50 kGy. The aqueous solution of metal/polymer creating hydrated electron, primary radicals and molecules upon the irradiation process. The optical properties were employed by using UV-Visible spectrophotometer to examine the optical properties of Cu and Cr nanoparticles. The absorption peaks for Cu and Cr nanoparticles dispersed in PVA and PVP have been observed increase with increase of -irradiation doses and demonstrates slightly blue shift due to the smaller particles size with increase of dose. The absorption spectra of Cu and Cr nanoparticles were analyzed further for absorption edge and energy of conduction band. From the plot of absorption coefficient versus photon energy h, the absorption edge of both nanoparticles was found increases when the dose increases for Cu and Cr nanoparticles dispersed in both PVA and PVP polymer matrix. The energy of conduction band of Cu and Cr nanoparticles was determined by the photon energy equation, Ecb = hc/maxwhere h is Planck’s constant, c is the speed of light and max is the wavelength value of maximum intensity of surface plasmon peaks. The value of energy conduction band calculated from the photon energy equation was found to be increases as dose increase up to 50 kGy for both Cu and Cr nanoparticles dispersed in PVA and PVP polymer matrix. The crystalline structure of Cu and Cr nanoparticles dispersed in PVA and PVP polymer matrix was investigate through X-ray diffraction analysis. Pure metallic Cu with face-centered cubic structure was observed for all irradiated samples dispersed in both PVA and PVP polymer matrix. Cr nanoparticles dispersed in PVA and PVP was observed with body centered cubic structure. The intensity of both Cu and Cr nanoparticles dispersed in PVA and PVP increased with increase of -irradiation dose. The size of Cu and Cr nanoparticles was determined by TEM analysis. The size of the nanoparticles was observed to be decrease with increase of gamma radiation doses. The average size of Cu and Cr nanoparticles dispersed in PVA is smaller than dispersed in PVP because of the polymer chain of PVA is longer than PVP. The agglomeration process of Cu and Cr nanoparticles occurred more in PVP polymer matrix due to the shorter polymer chain

Synthesis and optical characterization of Co nanoparticles dispersed on polymer matrix by gamma radiation

Cobalt nanoparticles were synthesized using reduction of 60Co gamma source with dose range 10-50 kGy in the presence of polyvinyl alcohol (PVA) polymer as a capping agent. Radiation synthesis has the advantages of without the use of reducing agent and catalyst and the cobalt nanoparticles aggregated immediately upon irradiation. The Ultraviolet-visible spectrophotometer and Nanophox measurement revealed the formation of cobalt nanoparticles by exhibiting surface plasmon absorption maxima at 500 nm. The size distribution of the cobalt nanoparticles was influenced by the concentration of CoCl2 and absorbed dose of gamma rays irradiation