Fractal and dendritic growth of metallic Ag aggregated from different kinds of γ-irradiated solutions

With gamma-irradiation on AgNO3 dissolved in deionized water, ethanol, and 0.01 M C12H25NaSO4, metallic Ag with different dispersed states and particle sizes was obtained. In the former two solvents, metallic Ag particles precipitated From the solutions and the Ag particle size was about 100 and 20 nm, respectively. In the latter solvent, Ag colloid was produced. The morphology of structures formed during two-dimensional aggregation of Ag particles in three different solvents was studied by transmission electron microsocopy (TEM). The patterns were dendrite, fractal (with center), and fractal (no center) with the fractal dimension of 1.81, 1.73, and 1.70 corresponding to the aggregating structure from deionized water, ethanol, and 0.01 M C12H25NaSO4 solutions, respectively. The formation mechanism of different patterns was illustrated from different aspects.