Morphology and Structure of Nickel Nuclei as a Function of

7/29/2019 Morphology and Structure of Nickel Nuclei as a Function of

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ELSEVIER Journal of Electroanalytical Chemistry 397 (1995) 11 1~ I8

Morphology and structure of nickel nuclei as a function of the conditionsof electrodeposition

E. Gb mez, R. Pollina, E. Vall&Departanzent de Quhica Fhica, Faculfat de Quimica, Unicersitat de Barcelona, Marti i FranquPs 1. 08028 Barcelona. Spain

Received 3 January 1995; in revised form 2 May 1995

AbstractA study of nickel n uclei deposited on a vitreous carbon electrode from chloride baths was performed at several pH values

(1 < pH < 4.5). The effects of growth rate (affected by the temperature and/or the nickel concentration), bath composition and depositiontime (particularly at low overpotentials) on the morphology of nickel nuclei were analysed. Before coalescence and during the early stagesof deposition, the morphology of the nuclei was influenced by the bath composition. When solutions with a high concentration of chlorideions were used. a characteristic star-shaped morphology was obtained which was attributed to the adsorption of chloride complexes, Thismorphology was related to the results obtained from impedance spectroscopy diagrams.Keywords: Electrodeposition conditions; Impedance spectroscopy; Texture; Morphology; Nickel nuclei

1. Introduction

There have been many studies of nickel electrodeposi-tion from a variety of electrochemical baths, and themorphology and texture of the final deposits have beenrelated to the domin ant process in each case [l-19].

It is generally accepted that the growth of depositsduring electrodep osition is influenced first by the substrate(epitaxial growth) and, when this influence disappears, bythe deposition conditions (bath composition, applied cur-rent or potential and pH). When deposition takes place onan amorphous substrate, epitaxial control does not occurand orientation of the deposits depends only on the deposi-tion conditions. Although there have been many observa-tions of nickel electro depos its using both transmission andscanning electron microscopes, they have provided littleinformation on the development of the nuclei and thefactors that affect it.

Nick el de position in a chloride medium is an inhibitedcomplex process [20]. In previous studies the effects ofseveral experimental variables (Ni(I1) and Cl- concentra-tion, pH, overpotential or applied current density andsubstrate) were analysed as a function of the quality of theresulting deposits. Ranges for these conditions were estab-lished such that acceptable deposits were obtained.

Owing to the obvious dependence of the final depositon the deposition conditions, we were interested in0022.0728/95/$09.50 0 1995 Elsevier Science S.A. All rights reservedSSDl 0022-072X(95)04202-4

analysing the develop ment of the nuclei un der the influ-ence of experimental factors. The aim of this study was toestablish the way in which the species present in thesolution affect the growth of the nuclei and to establishwhich species were responsible for certain types of growth.

The shapes of the first nuclei were analysed for differ-ent deposition conditions, with the proviso that the nucleidid not overlap completely.

Vitreous carbon electrodes were chosen for this studybecause of the lower nucleation rate on carbon comparedwith metallic electrodes. Thus the overlap of the nuclei canbe delayed such that the size of the nuclei is increased.Moreover, epitaxial control by the substrate is avoidedwith vitreous carbon.

2. Experimental detailsNiCl, 6H ,O, NiSO, 6H ,O and NaCl (analytical

grade) were obtained from Merck. T he solutions werefreshly prepared with water from a Millipore Mini-Qsystem. Ni(I1) solutions were prepared from chloride orchloride + sulphate salts with Ni(I1) concentrations rangingfrom 0.5 to 2 M. When necessary the pH was adjusted bysuitable HCl or NH ,OH additions. The temperature waskept constant at 20C except in investigations of the effectof temperature when a Haake D8 cryostat was used.


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I I2 E. Ghez et al. / Journal c~Electmanc~lytica1 Chemistry 397 (1995) II I-118

A conventional thermostated three-electrode cell wasused. The working electrode was a Metrohm vitreouscarbon rod (diameter 2 mm), w hich w as polished to amirror finish before e ach run using alumina of differentgrades (3.75. 1.87 and 0.3 km) and cleaned ultrasonicallyfor 2 min in water. The surface state of the electrode wasmonitored by optical microscopy using an OlympusPMG C3 metallographic microscope.

A rotating-disc electrode (RDE ) w ith an iron rod (2 mmdiameter) in a Teflon support was used for the impedancecxpcriments. The iron working electrode was polished to amirror finish using diamond of different grades (6, 1 and0.25 pm> and washed ultrasonically for 2 min in water.

The counter-electrode was a nickel sheet (JohnsonMatthey 99.99% ) and the reference electrode was aAg lAgC1 from Metrohm , mounted in a Luggin capillarycontaining 1 M NaCl.

Voltamm ctric and potentiostatic experiments were car-ried out using a Belport 105 potentiostat together with aPAR 175 signal generator and a Philips P M 8133 X-Jrecorder. The galvanostatic measurements were obtainedusing a PAR potentiostat model 273 controlled by a Tan-don 386 SX20 computer.

The impedance spectra w ere obtained using a Schlum-berger 1 255 frequency-response analyser linked to an EG& G potentiostat model 2 73. The impedance was measuredbetween 10 and 5 X 10e4 Hz.

The morphology of the deposits was examined usingeither a Leica Cam bridge Stereoscan S360 or a HitachiS2300 scanning electron microscope.

The microstructure of the deposits was examined usinga Hitachi H800N A transmission electron microscope(TEM) at an accelerating voltage of 200 kV.

The specimens for the TEM studies were cross-sectionsof deposited electrodes. The deposits were protected bycoating the electrode surface w ith an adherent wax film.Then the electrode was cross-sectioned, polished withdiamond paste and ion milled (argon). The samples wereexamined directly without using a replica.

3. ResultsOur previous studies of nickel deposition on vitreous

carbon in chloride media [20,21] showed voltammetriccurves with a complex reduction peak (Fig. l(a)) whichwas related to an inhibition process. Potentiostatic experi-ments at the optimum conditions established previously(0.5 M NiCl, and pH 3) showed that at low overpotentialsthe j-t transients had a normal dependence on potentialwith a monotonic increase in current with time (Fig. I(b),curve (a)), leading to a compact bright deposit. Morpho-logical studies revealed that the deposition began withdense polyhedrical nuclei of hemispherical symmetry,leading to a compact cauliflower-like deposit [20].

When the overpotential was increased, the current de-

(a) j t mA Cm

(7I : ,/ \-0.5 E/V

-1

1

-2o--

b) j/mAcm-2

Fig. 1, (a) Cyclic voltammogram of 0.5 M NiCI, solution (pH 3; c = 50mV 5-l at lower limits of -1080 mV (-----I and - 1480 mV( ---_); (b) potential step transients for nickel deposition from -SO0mV to (a) -910 mV, (b) -930 mV, and (c) -985 mV in 0.5 M NiCI,solution (pH 3).

creased after a certain time (Fig. l(b), curve (b)). At higheroverpotentials the j-t curve showed a clear first peakfollowed by a sharp fall and posterior growth (Fig. l(b),curve (c)). Samples deposited in this way had flat blackinhibited deposits.

It was established that Hads was present throughout thepotential range but it did not have a deleterious effect onthe growth of deposits. Howe ver, when high overpotentialswere applied, the local pH varied and nickel hydroxidesprecipitated owing to the sharp increase in hydrogen pro-duction. The hydroxide precipitation was related to thesteep decrease in current observed in the j-t transient.Howe ver there was a range of conditions where thisinhibition was delayed.

As the morphology of the final deposit depends stronglyon the experimental conditions, an analysis of the mor-phology and shape of the nuclei before coalescence wasmade varying b oth electrochemical and solution composi-tion parameters.3.1. Influence of overpotential or current density

A number of experiments were performed in the poten-tial range where the j-t transients showed a monotonic


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increase in current, always at potentials at which hydrogenevolution did not occur on the vitreous carbon electrode. Aseries of experiments were performed in which the deposi-tion charge or the deposition time was kept constant. Asexpected, at a fixed charge, high overpotentials induced alarge number of nuclei whereas for low overpotentialsfewer nuclei of larger size were obtained.In the fixed ch arge experiments (Q = 5 mC>, the nucleiobtained in the potential range between - 750 and - 9.50mV have a radial structure and a polyhedral shape (Fig. 2).Similar nuclei were obtained using galvanostatic deposi-tion at low current densities (j < 5 mAcm _*), for whichth e E- t transient shows the typical nucleation spike fol-lowed by a stationary potential value.

As the deposition time is increased, the nuclei becomemore structured as a consequence of either the differentgrowth rates of the crystallite facets or the adsorption ofH Ods on the deposited nickel. The adsorbed H slowlyevolved to H? at these potentials [22-241.

When potentials more negative than - 1000 mV areused and the j-t transient correspo nds to a clearly inhib-ited process, changes in the deposition process are ob-served. The first nuclei obtained quickly coalesce to athick passivated film (cracked film in Fig. 3) whose struc-ture is difficult to observe. Howev er, a second nucleationstage can bc seen in this film. This stag e, which is lessextended owing to the high coverage of the surface bynickel hydroxides, corresponds to hemispherical nuclei atshort deposition times w hich can be seen as rounded nucleion the cracked film in Fig. 3. The presence of precipitateson the electrode reduces the number of nucleation sites sothat very few nuclei grow to a considerable size in a shortdeposition time owing to the high overpotential. Whenhigh growth rates arc observed, growth does not take placein preferential directions and spherica l nuclei are obtained.Howev er, at longer deposition times in these conditions thefinal deposits are cracked films [21] composed of star-

Fig. 2. Scanning electron micrograph of a nickel deposit obtained from0.9 M NiClz solution (pH = 3): I5 min at -770 mV; Q = 5 mC.

Fig. 3. Scanning electron micrograph of a nickel deposit obtained from0.5 M NiCI, solution (pH 3): 40 s at - 1010 mV; Q = 24 mC.

shaped crystallites owing to the formation of nickel hy-droxyl species w hich inhibit the growth in some directions.In galvanostatic deposition, at j > 5 mA cm-, the E- tcurves display a narrow spike followed by stabilizationcorresponding to growth of the initial nickel deposited andthen the evolution of the potential to more negative valuesand a new stationary value at which hydrogen evolutionand nickel deposition take place simultaneously. When thedeposition follows this type of E- t curve, the morphologyof the deposits is similar to that obtained using potentio-static techniques at potentials more negative than - 1000mV.

On the basis of these results, the influence of theremaining parameters on the formation of nickel crystal-lites was studied potentiostatically mainly at low overpo-tentials at which monotonic j-t transients are obtained.3.2. Temperature effects

Nickel deposition was studied at different temperaturesto determine the sequence in which the morphology of thenuclei was modified. The temperature range selected was5-45C.

Although the increase in temperature advances the onsetof deposition, it does not extend the relative potentialrange in which th e inhibition processes are not clearlymanifested. As the temperature increases the process maytake place more easily and at a higher deposition rate, butthis temperature increases is insufficient to raise the solu-bility of the alkaline nickel salts formed at the interfacebetween the deposit and the Ni solution during the process.The increase in local pH leads to the precipitation of thesehydroxyl species. At these temperatures the depositionproce ss begins a t lowe r potentials but inhibition also oc-curs sooner.

Polyhedral nuclei are obtained at all temperatures, withmore structured nuclei at low growth rates. The scanningelectron m icrographs were used to estimate the growth rateL:~of nuclei; uZ was evaluated from the change in the size


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Table 1Effect of temperature T on the growth rate u, of the nickel nucleiT/C 10 cg /cm s-10.4 0.3620.0 I 629.2 3.039.5 8.3

of the nuclei with increasing deposition time (Table I). Ata fixed potential, it was found that the growth rate in-creased on increasing the temperature but the shape of thenuclei did not show any structural modifications.3.3. Effect of Ni(ll) concentration

Since more spherical nuclei were expected with increas-ing growth rate, experiments were performed at a higherconcentration (2 M NiC12).

Surprisingly, the nuclei deposited from 2 M NiCl,solution are not spherica l but star-sha ped under all condi-tions (Fig. 4). Two series of experiments were performed,one analysing the effect of varying the applied potentialwhile keeping the charge constant (Q = 5 mC> , and theother studying the potentiostatic deposition at several de-position times. In these experiments the nuclei becam edenser as the overpotential increased, and the edges be-came sharper as the deposition time increased. This kind ofmorphology can be related to the possible adsorption ofspecies present in solution during grow th of the initialcluster.

In order to determine the extent to which the presenceof chloride ion was responsible for the growth of thenuclei in characteristic directions, the extra chloride ionwas replaced by a sulphate ion, maintaining the total Ni(I1)concentration at 2 M. Solutions of 0.5 M NiCl, + 1.5 MNiSO, at pH 3 were used.

Potentiostatic j-t transients for this solution have asimilar shape and current values to those obtained for the

Fig. 5. Scanning electron micrograph of a nickel deposit obtained from0.5 M NiCI, + I.S M NiSO, solution (pH 3): 100 s at -830 mV; Q= 5mC.

chloride solution, but are shifted towards more negativepotentials. The difference in characteristic potentials forchloride and sulphate media h as been explained on thebasis of the different activity coefficients in sulpha te andchloride solutions [25,26].

Morphological studies show that, even at very lowoverpotentials and/or high deposition times, the nucleinever display an edged morphology. Instead, they arealways dense polyhedra (Fig. 5). How ever, when the depo-sition is performed from a solution containing 0.5 M NiCl,and NaCl salt to give a chloride concentration of 4 M, thenuclei hav e the characteristic star-shape (Fig. 6). Thisresult demonstrates that the excess chloride in the mediuminduces changes in the nickel growth.

Deposits obtained after coalescence are also different.When dep osited from chloride + sulphate solution, theyhave characteristic cauliflower morphology (Fig. 71 similar

Fig, 4. Scanning electron micrograph of a nickel deposit obtained from 2M NiCI, solution (pH 3): 100 s at -720 mV; Q = 5 mC.

Fig. 6. Scanning electron micrograph of a nickel deposit obtained from0.5 M NiCI, + 3 M NaCl solution (pH 3): 400 s at - 860 mV; Q = 5mC.


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E. G6mez et al. /Journal of Electroanulytical Chemistry 397 (1995) I I1 - 118 11 5

Fig. 7. Scanning electron micrograph of a nickel deposit obtained from0.S M NiClz + I.5 M NiSO, solution (pH 3): 70 s at - 880 mV; Q = SmC.

to that obtained from the 0.5 M NiCl, solution, whereasdeposits from 2 M NiCl, or 0.5 M NiCl, + 3 M NaClsolutions have a sharp-edged morphology (Fig. 8).

The nickel crystallites, imaged by TEM without specialpreparation, are star-shaped where their hemispherical en-velope is penetrated by acicular crystals (Fig. 9).Selected-area diffraction studies of the crystallites showedspotty diffraction rings which revealed their polycrystallinenature and the very small size of the crystalline domains.

Studies o f the crystallites using convergent beam elec-tron diffraction with a spot size of 2 nm showed differentorientations when different points on the crystallite werechosen, although no preferential orientation was found.Despite the different final morphology, these results are ingood agreement with those obtained for nickel depositedfrom 0.5 M NiCl, [27].

Fig. 9. Transmission electron micrograph of nickel crystallites obtainedfrom 2 M NiCI, solution (pH 3): 300 s at -730 mV.

3.4. Effect of pHSeveral solutions were prepared with pH values in the

range 1.0-4.5 and all other conditions kept constant. Theoverpotential used for each potentiostatic deposition wasselected so that the shape o f j-t transients and the chargewere kept constant during the experiments. A direct com-parison of morphological results obtained at different p Hvalues is possible in this pH range [20].

As expected, polyhedral nuclei were deposited from 0.5M NiCI, solution and 0.5 M NiCl, + 1.5 M NiSO, solu-tions throughout the potential range analysed and all thepH values studied. W hen 2 M NiCI, solutions were used,the nuclei were star-shaped for all pH values within therange (Fig. 10); however, at lower p H values the nucleiwere more rounded with smoother edges.3.5. impedance measurements

Two sets of impedance measurements were obtainedusing solutions with a fixed Ni(I1) concentration and a

Fig. 8. Scanning electron micrograph of a nickel deposit obtained from 2M NiCI, solution (pH 3): 2 min at -814 mV.

Fig. 10. Scanning electron micrograph of a nickel deposit obtained from 2M NiCI, solution (pH 4.3: 160 s at - 685 mV; Q = 5 mC.


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d) C)11oooL-E/mV

i60 0 700 800 900 1000

-E/mVFig. Il. Steady-state polarization curves for nickel deposition onto aniron electrode (area 0.03 I4 cm) from solutions of various compositions(pH 3): (a) 0.5 M NiC12 + 1.5 M NiSO,; (b) 2 M NiCI,; (c) 0.5 MNiCl,; (d) 0.5 M NiCI, + 3 M NaCl. Rotation rate, 3000 rev min-.

variable chloride content, one at 0.5 M Ni(I1) (from either0.5 M NiCl, or 0.5 M NiCl, + 3 M NaCl solutions) andthe other at 2 M Ni(I1) (from 2 M NiCI, or 0.5 MNiCl, + 1.5 M NiSO, solutions). Since similar behaviourhas been found for nickel electrodeposition from a chloridemedium onto different substrates (vitreous carbon, nickel,iron and platinum electrodes) [27], the impedance measure-ments were made on an iron electrode to ensure theformation of more adherent deposits.

The polarization curves obtained are shown in Fig. 11.They show that the presence of excess chloride in thesolution activates the electrodeposition process, i.e. at agiven potential the deposition is easier from solutions witha high chloride content. The corresponding impedanceplots for a fixed current of 0.1 mA are shown in Fig. 12.

The impedance plot for a 0.5 M NiCl, + 1.5 M NiSO,solution (Fig. 12(A )) shows a capacitive loop (100 Hz) andan inductive feature (below 1 Hz). When the experimentwas repeated using a solution with the same Ni(KI) concen-tration but containing only the chloride salt (2 M NiCl,),two clear inductive loops were detected (Fig. 12(B)). Thusit is evident that the excess chloride ion has an influenceon the electrodeposition process.

250: (4

zoo-

150-

I OO-

5O-

O-10 SC

- 54

250: 03

iw

250

__ (4250

Fig. 12. Complex plane impedance plots at points A, B, C and D on thepolarization curves


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E. G6mez et al. /Journal of Electroanalytical Chemistry 397 (I 9951 1 I -I 18 117

Differences in the impedance plots were also observedfor solutions containing 0.5 M Ni(I1) and variable chlorideconcentrations. For 0.5 M NiCl, solutions, a single induc-tive loop followed by a capacitive loop was obtained (Fig.12(C)); the latter is related to inhibition of the process byadsorbed hydrogen. How ever, when 0.5 M NiCl, + 3 MNaCl solution was used, the impedance plot showed asecond loop at very low frequencies (below 4 mHz) (Fig.12(D)). This second loop in Figs. 12(B) and 12(D) isrelated to anion d esorption when excess chloride is presentin solution.

When the impedance diagrams were recorded at cur-rents above 0.1 mA, the second inductive loop graduallybecame smaller and eventually disappeared.

4. DiscussionA fundamental electrochemical and morphological study

of the initial form ation of nickel crystallit es on vitreouscarbon has shown that experimental conditions such asoverpotential, current density, temp erature and bath com-position influence the growth process from the early stagesuntil coalescence.

The nuclei deposited from solutions containing either0.5 M NiCl, or sulphate show a radial structure for shortdeposition times. It is known [22-241 that these nucleidevelop polyhedral structures as a consequence of thedifferent growth rates of the crystallite facets, and that thisis also influenced by the different adsorption capacity ofthe hydrogen produced during nickel deposition.

In these conditions the presence of either adsorbedhydrogen or complexes in solution does not seem to affectthe growth of nickel deposits, so that coherent and com-pact deposits are obtained at potentials less negative than_ 1000 mV. When the crystal growth is faster (applicationof sufficient overpoten tial or current density), th eanisotropic distribution of the surface Gibbs energy isminimized [24] and, in addition, Hads evolved to hydrogenmore easily, allowing the crystallites to become denser andpolyhedral forms to become spherical. Howev er, localprecipitation of nickel hydroxides at high overpotentials orhigh current densities has a dramatic effect on nickelgrowth.

In contrast, nuclei formed at short deposition timesfrom solutions with high chloride content develop intostar-shaped crystallites with sharp edges. Such a character-istic growth mode is due to the species present in the bath.In this case, the possibility of direct adsorption of chlorideanions is rejected in this potential range.

Many different nickel complexes can appear in nickelsolutions at different pH values [28]; Ni(I1) can be presentin solution in the form of hexaquo-nickel complexes whenthe solution pH is very low. At a pH near 3 watermolecules of the coordination sphere may deprotonatequickly leading to the formation of aquo-hydroxy nickel

complexes. Moreover, deprotonation is known to labilizethe H,O in the coordination sphere, thus facilitating theincorporation of other ligands such as OH- or Cl-. There-fore chloro-hydroxy nickel complexes may exist at highchloride ion concentrations. The participation of sulphatein the nickel coordination spher e is less likely, and onlyaquo or aquo-hydroxy nickel complexes are formed insulphate media.

The different morphology observed in nickel crystallitesobtained in baths with high chloride contents may berelated to the predominant existence of chloro-hydroxynickel complexes in solution. These complexes adsorb onnickel crystallites and either hinder or favour gro wth of thedeposit in certain directions. These complexes are formedextensively in solutions with high chloride concentrationsor when the ratio of chloride to nickel in the solution ishigh. The suggestion that adsorption of chloro-complexesis responsible for this characteristic growth is in goodagreement with the morphology observed for nickel crys-tallites deposited from 0.01 M NiCl, + 1 M NaCl solution[29]. Nickel crystallites with a star-shaped morphologywere also obtained from this solution. Howev er, underconditions where hexaquo-nickel complexes are the mainform of nickel (pH < 1) and the existence of hydroxy-chloro complexes is not favoured, the nuclei obtained aremore polyhedral and rounded.

The results of impedance spectroscopy can also beinterpreted in terms o f the role played by these chloro-hy-droxy nickel complexes. The impedance diagrams for solu-tions investigated have a common inductive feature. Thisfirst inductive loop has been related to the monovalentintermediate NiOH,,, proposed in the mechanism fornickel deposition [30]. In addition to this feature, a secondinductive loop appears at low frequencies for solutionswith a high chloride concentration; it is related to adesorption process [30,3 11.

When th ere is sufficient chlorid e in solution to allowthe formation of chloro-hydroxy complexes, they adsorbon the electrode and their desorption causes the appearanceof the second inductive loop in the impedance diagram.The adsorption of these complexes can be prevented byusing higher current densities whereupon the second induc-tive loop disappears from the impedance diagrams.

Thus the results obtained from the impedance measure-ments also imply that a mechanism for nickel depositionfrom a bath with a high chloride content must take intoaccount the presence of chloro-nickel complexes as ad-sorbed inhibiting agents.

In view of the reproducibility of all these features aswell as the large differences in the morphologies of crys-tallites obtained from the various baths, the results indicatethe existence of different adsorption processes in the depo-sition mechanism. The prevalence of these mechanismsdepends on the bath composition.

When conditions are favourable for the formation of thechloro-hydroxo complexes, these species produce struc-


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118 E. Ghnez et al. / Journal cf Electroan alyticnl Chem istry 397 (19951 I II -I 18

tural modifications in the nickel crystallites. Howe ver,whatever th e characteristic morphology, the structuralanalysis did not reveal the preferential growth orientationsexpected on vitreous carbon [ 11,141.

In conclusion, the deposition parameters (temperature,overpotential, current density) affect the morphology of thedeposits on an amorphous substrate, even in the earlystages. However, bath composition has the strongest influ-ence, with the presence of species that may adsorb on thedeposit being particularly important. These species may bepresent either in the freshly prep ared bath (chloro-hydroxycomplexes) or may be formed during the electrodepositionprocess (NiOH,,,, Hads, Ni(OH ), etc.).

Acknowledgements

The authors are indebted to the Servei de Microscbpiai Espectroscbpia of the Universitat de Barcelona for helpwith the SEM and TEM studies. They gratefully acknowl-edge financial assistance from the Comision de Investi-gacion Cientifica y Tecnica (Project MAT 94-1338).

References

[II12 1[31[41

B.C. Banerjee and A. Goswani, J. Electrochem. Sot., 106 (1959) 20.B.C. Banerjee and P.L. Walker, J. Electrochem. Sot., 109 (1962)436.R. Weil and H.C. Cook, J. Electrochem. Sot., 109 (1962) 295.J.A. Crossley, P.A. Brook and J.W. Cuthbertson, Electrochim. Acta,I I (1966) 1153.

[Sl M. Froment and G. Maurin, J. Microsc. (Paris), 7 (1968) 39.[61 1. Epelboin, M. Froment and G. Maurin, Plating, 56 (1969) 1356.[71 S. Nakahara and R. Weil, J. Electrochem. Sot., 120 (1973) 1462.

l81[91

[IO1

[III

[121[I31

[141

[ISI[I61

[I711181[191001

[211

Ed[231

[241

WI

[261

[271

[281

[291

[301

[311

J. Amblard, M. Froment and N. Spyrellis, Surf. Technol., S (1977)205.J. Amblard, 1. Epelboin, M. Froment and G. Maurin, J. Appl.Electrochem., 9 (1979) 233.8. Nayak and K. Karunakaran, J. Appl. Electrochem., 12 (1982)323.J. Amblard, M. Froment, G. Maurin, D. Mercier and E. Trevisan-Pikacz, J. Electroanal. Chem., 134 (1982) 345.M.Y. Abyaneh. Electrochim. Acta, 27 (1982) 1329.0. Teschke and D. Menez Soares, J. Electrochem. Sot., I30 (1983)306.J. Amblard, M. Froment, G. Maurin, N. Spyrellis and E. Trevisan-Souteyrand, Electrochim. Acta. 28 (1983) 909.M.L. Lain and D. Pletcher, Electrochim. Acta, 32 (1987) 99.R. Ragauskas and V. Leuksminas. Sov. Electrochem., 24 (1988)675.A.A. Sambi and V.B. Sing, J. Electrochem. Sot., I36 (1989) 2950.C. Kollia, N. Spyrellis, J. Amblard, M. Froment and G. Maurin, 1.Appl. Electrochem., 20 (I 990) 1025.A.A. Vikarchuk, Sov. Electrochem., 28 (1992) 805.E. Vallts, R. Pollina and E. Gomez, J. Appl. Electrochem., 23(1993) 508, and references cited therein.E. G6mez, C. Muller, R. Pollina, M. Sarret and E. VallCs. J.Electroanal Chem., 333 (1992) 47.A.K.N. Reddy, J. Electroanal. Chem., 6 (1963) 141.N.A. Pangarov, J. Electroanal. Chem., 9 (1965) 70, and referencescited therein.E.I. Girargizov, Oriented Crystallization on Amorphous Substrates,Plenum Press, New York, 199 I.J. Yeager, J.P. Gels, E. Yeager and F. Hovorka, J. Electrochem.Sot., 106 (1959) 328.I. Epelboin, M. Joussellin and R. Wiart, J. Electroanal. Chem., 1 I9(1981) 61.E. G6mez, R. Pollina and E. Vallts. J. Electroanal. Chem., 386(1995) 4s.R.M. Smith and A.E. Martell, Critical Stability Constants, Vol. 4,Plenum Press, New York, 1976.E. Gomez, C. Muller, W.G. Proud and E. Valles, J. Appl. Elec-trochem., 22 (1992) 872.R. Wiart, Electrochim. Acta, 35 (1990) 1587, and references citedtherein,E. Chassaing, M. Joussellin and R. Wiart, J. Electroanal. Chem.. IS7(1983) 75.

Morphology and Structure of Nickel Nuclei as a Function of

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