Nickel electrocrystallization—from nucleation to textures

TEM examinations of cross-sectioned Ni electrodeposits grown on oriented substrates show that their structure results of a competition between an epitaxial growth process and a non-epitaxial growth initiated by a substrate-independent nucleation. This independent nucleation is a necessary step prior to the progressive development of a definite fibre texture in thicker deposits. Both processes have been investigated separately on two kinds of cathodic substrates (either single crystals or amorphous carbon) by means of a permanent correlation between structural examinations and transients analysis. Results show that for an amorphous substrate multitwinned particles with a roughly hemispherical shape are generated by independent nucleation. Models are given which account well for experimental current—time transients. The situation is more complex when the substrate is a low-index plane of a single crystal (Cu or Ni) in which case several competitive growth processes are contribution to the whole current.