Unsteady growth of ammonium chloride dendrites

Growth of ammonium chloride dendrites from aqueous solution is experimentally investigated. The growth rate υ and the radius ρ of curvature of branches are measured as a function of the relative supersaturation Δ for steady and unsteady growth conditions. It is shown that the experimental results are quantitatively described by the dependences ρ=a/Δ+b, υ=сΔ2, where the factors for primary branches are a=(1.3±0.2)·10−7 m, b=(2.5±0.4)·10−7 m, and c=(2.2±0.3)·10−4 m/s. The factor c is found to be approximately 7 times smaller for the side branches than that for the primary branches.