OPTICAL-ABSORPTION OF COMPOSITES OF NANOCRYSTALLINE SILVER PREPARED BY ELECTRODEPOSITION

Silver particles of average diameters in the range 10.3-25.7 nm have b een grown within a gel medium by an electrodeposition technique. Detai led optical absorption characteristics in the wavelength range 250-600 nm have been investigated for nanocomposites comprising these particl es dispersed in a polystyrene matrix. Absorption maximum occurs at a w avelength around 350 nm, which increases as the metal particle size is increased. Mie theory with the incorporation of a distribution of par ticle size gives remarkable agreement with the experimental data. The electrical conductivity as extracted from the theoretical analysis for particles with diameters similar to 3 nm is found to be less than Mot t's minimum metallic conductivity. This indicates the possibility of a metal insulator transition in this system, which appears to be consis tent with earlier electrical conductivity measurements. (C) 1998 Ameri can Institute of Physics.