2007 Volume 48 Issue 11 Pages 2888-2892
The effect of magnetic fields on electroless silver deposition was investigated through in situ microscopic observation using a periscope system developed on the basis of a confocal scanning laser microscope. At the growth front of a silver dendrite, under a 12 T magnetic field applied perpendicularly to the sample plane, a straight silver branch was grown for a while; then, a given length of the branch at the neighbor of the tip started moving rapidly and was bent in an integrated manner. As a result of the process, a dense silver dendrite in the shape of a vortex was formed. When the sample space was narrowed, the branch did not bend due to the increase in the static friction between the branch and the glass plates. Judging from these observations, the mechanism underlying the formation of a dense vortex dendrite was thought to be the effect of the Lorentz force acting on the branch due to the electric current flowing through the branch itself accompanied by the silver deposition and the copper dissolution reactions. Furthermore, the reason that the silver dendrite grown under high magnetic fields looked denser by macroscopic observation was investigated by evaluating the reaction amount and the microstructure of the silver branch. No significant difference was observed in the reaction amount between the experiments with and without magnetic fields. On the other hand, the microstructures of the silver branch were significantly different from each other. The silver branch grown under high magnetic fields had a low-density structure, which seems to account for its denser appearance in the macroscopic observation. This low-density structure may be formed because of the interference of the static crystal growth due to the rapid bend of the silver branches.