科研之友
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摘要
Deposition, diffusion, and aggregation (DDA) on percolation substrates were investigated by computer simulations. The nonuniform degree of the substrate is described by the occupied probability p, by which the percolation is generated. p takes values in the range p(c)<pless than or equal to1, where p(c) is the threshold of percolation. The blocked sites in percolation represent the defects in the substrates. The interactions between defects and deposited particles are involved by introducing the sticking coefficient s. For inert defects (s=0), the defects hinder the deposited particles from diffusing in the substrates. As p decreases from 1 to p(c), the morphology of the aggregates varies from the DDA pattern on uniform substrates to the few-and-zigzag-branch pattern. For active defects (snot equal0), the defects play a role in absorbing the deposited particles also. With the reduction of p from 1 to p(c), the pattern of aggregates changes from DDA on uniform substrates to a site-percolation-like pattern (for s=1) or a dispersed-small-island one (for 0<s<1) on critical percolation substrates. A rapid increase of the fractal dimension D-f of aggregates appears in the D-f-p curve, which corresponds to the transition of morphologies from a pattern dominated by defects to one controlled by diffusion. Moreover, our simulations show that the Honda-Toyoki-Matsushita relation is reasonable for growth controlled by defect-hindering diffusion in fractional spaces.
- 出版日期2002-6-15
- 单位武汉大学
