Crystallographic and morphological studies of electrolytic zinc dendrites grown from alkaline zincate solutions

Abstract

Electrolytic zinc dendrites grown potentiostatically from a range of alkaline zincate solutions were studied using X-ray diffraction and scanning electron microscopy (SEM) to reveal structural and morphological characteristics as a function of their growth rate. Conclusions from this work were as follows: Dendrites grown at a rate of 3 μm min−1 were identified as twinned monocrystalline “swords” with a noticeable absence of regular branching. Dendrites grown at a rate of 24 μm min−1 were basically twinned monocrystals with some polycrystalline character. As for the slowest growing dendrites, the morphological character was of a sword-like nature. Morphologically these first two types of dendrites show great similarity to the butterfly dendrites of DeVries. Dendrites grown at 67 μm min−1 were of the fern-like morphological type with a large degree of polycrystalline character. These dendrites are suggested as being composites of very small slow growth rate dendrites in a roof tile arrangement. The results for the ideal fern-like dendrites seemingly disagree with the earlier hcp dendrite work of Wranglen who identified this type of dendrite as a monocrystal. An explanation for this discrepancy is offered. The work presented here appears to be consistent with the twin plane re-entrant edge (TPRE) growth mechanism.