Synthesis and Characterization of Ag/PVP Nanocomposites by Reduction Method

A polyvinylpyrrolidone (PVP)/Ag nanocomposite was prepared by reduction of silver nitrate in ethylene-glycol in the presence of a polymeric protective agent (i.e., poly (N-vinylpyrrolidone)). The size dependent color variation of this nanocolloid is a clear indication of the presence of Ag as nanoparticles in the polymer matrix. The nonlinear optical properties were studied by Z-scan technique in which a Q-switched Nd: YAG laser with a pulse width of 7 ns at 532 nm was used as the source of light. Z scan measurement shows that Ag/PVP exhibits third order Nonlinear Optical effects. The peak-valley curve from closed aperture measurement indicates the self-defocusing process. The third order nonlinear optical parameters n2, β, χ3 are found to be of the orders of 10−9 esu, 10−9 m/W, 10−11 esu respectively. The very strong Plasmon resonance peak at 419 nm was observed and is a clear consequence of the nanosize of dilute Ag particles. The optical band gap of this nanomaterial was calculated as 2.535 eV. The XRD pattern indicates the presence of crystalline Ag and the average grain size was obtained as 17.4 nm. The SEM micrograph confirms this observation. Thermal Gravimetric Analysis implies that Ag/PVP nanocomposite exhibits high degree of thermal stability.