We experimentally found various patterns of precipitation in a lead iodide Liesegang system: periodic precipitation, continuous tree-like crystal aggregates and periodic tree-like crystal aggregates. Gel and reactant concentrations are two major controlling factors. At high gel concentrations, Liesegang band forms, whereas at low gel concentrations, tree-like crystal aggregates similar to diffusion-limited aggregation (DLA) develop in the entire system. At an intermediate gel concentration, Liesegang band and tree-like crystal aggregates coexist. At lower reactant concentration, the periodic tree-like crystal aggregates tends to form. A simple scaling argument that the kinetics of bulk and surface nucleation plays an important role, is presented to understand the effect of gel concentration on pattern transition.
All Science Journal Classification (ASJC) codes
- Statistical and Nonlinear Physics
- Mathematical Physics
- Condensed Matter Physics
- Applied Mathematics