A study of the morphology of nickel electrodeposits and the influence of substrate and electrolyte, using high resolution replication

Abstract

The morphology of nickel electrodeposits, formed on (100) and (111) single-crystal nickel substrates from Watts solutions of different purities, with various additions of coumarin, 1.3.6 naphthalene trisulphonic acid and Nisol 75, has been examined using a high-resolution platinum/carbon replica technique. The observations show that the growth of nickel electrodeposits is governed by the mutually opposing influences of the substrate and the solution, and that increasing organic additions progressively overcome the substrate influence in a way that relates to the morphologies of a series of addition-free Watts deposits of decreasing thickness. Scanning electron microscopy has been shown to be well suited to the general examination of nickel morphology. High-resolution replicas have revealed certain aspects of the behaviour of microsteps which are not fully explained by bunching theory; the observations also have significance for the development of kinetic models of electrodeposition.