Mc. Lefebvre et Be. Conway, Nucleation and morphologies in the process of electrocrystallization of aluminium on smooth gold and glassy-carbon substrates, J ELEC CHEM, 480(1-2), 2000, pp. 46-58
Complementary to work reported in the preceding paper and elsewhere on the
kinetics and mechanism of the elementary discharge steps involved in electr
ocrystallization of Al, studies are reported here on nucleation and growth
of the Al phase electrodeposited from solutions of AlCl3 and LiAlH4 in tetr
ahydrofuran onto two inert smooth substrates, glassy carbon and gold. Two p
rincipal compositions of the plating baths are investigated, chloride-rich
and hydride-rich, in which the speciations of dischargeable Al-complexes di
ffer, as characterized in our earlier work by means of Al-27-NMR spectrosco
py. Nucleation and growth transients are recorded in response to potential
steps of various amplitudes applied in the two types of baths. The response
currents are analyzed in terms of 'instantaneous' and 'progressive' nuclea
tion mechanisms, together with examination of the role of diffusion. Owing
to the chemical complexity of the species from which Al is deposited in the
se baths the two nucleation conditions cannot be distinguished clearly in t
he results obtained, although a large extent of replication of experimental
results was made. The nucleation and growth results are related to microsc
opic morpholgies of the Al electrodeposits photographed by scanning electro
n microscopy. (C) 2000 Elsevier Science S.A. All rights reserved.