The electrodeposition of cobalt + copper alloy on vitreous carbon, copper a
nd nickel electrodes in a citrate bath at pH ca. 5 has been studied for two
[Co(II)]/[Cu(II)] ratios in solution. Voltammetric and stripping results o
n vitreous carbon show that co-deposition of the two metals takes place und
er these conditions. Electrodeposition leads to the formation of a solid so
lution of cobalt in copper, detected by only one oxidation peak that shifts
from the copper to the cobalt position as the applied current density-appl
ied potential is made more negative. Structural XRD analysis and compositio
nal analyses, confirm the formation of a cobalt-copper solid solution of fa
ce-centred-cubic (fcc) structure. Diffractograms show peaks that appear at
diffraction angles between the lines corresponding to copper and fee cobalt
. The value of the fee lattice constant a of the alloy decreases linearly w
ith the increase in the cobalt percentage in the deposits, following Vegard
's law. Deposits obtained at the same charge and current density from the s
ame bath on different substrates have similar morphology: nodular-grained d
eposits at low deposition current densities-applied potentials, which evolv
e gradually to more fine-grained and structured deposits as the cobalt perc
entage in the deposits is increased. (C) 2000 Elsevier Science B.V. All rig
hts reserved.