Dendrites and growth layers in the electrocrystallization of metals

Abstract

Electrodeposited dendrites show a simple relation to the space lattice. The main type of dendrite in the f.c.c. lattice branches along [110]. At high c.d., Pb develops dendrites branching along [100]. Sn grows along [101] at low c.d. and along [110] at high c.d. Cd dendrites are complicated, but their main branching is along [100]. The dendrite directions are the closest packed directions in the lattice.Metals of low overvoltage grow by the lateral extension of layers, about 1 μ thick. At low c.d. (< 0·05 A/cm2), the layers start in the interior of the crystal faces whilst, at higher c.d., on edges and corners. Centre growth layers are usually generated by flat growth pyramids, more rarely by growth spirals. The planes of the growth layers are the closest packed lattice planes and are, in order of importance: for Pb, Ag and Cu, (111) and (100); for Cd, (001), and (100); for Sn (101) and (100). Inhibition increases the thickness and number of growth layers but decreases their rate of flow. Anodic dissolution of electrodeposited crystals also occurs by layers.