Preparation and characterization of electrodeposited iron + cobalt thin films from a chloride bath

Abstract

Ligas Fe-Co foram depositadas e dissolvidas em solução contendo íons metálicos e em solução de NH 4 Cl. Resultados voltamétricos sugerem interação entre os componentes da liga, originando uma solução sólida. Perfis de ALSV apresentam diferenciação para o processo de dissolução dos metais individuais e das ligas, com comportamento semelhante ao observado para cobalto e/ou ferro, com deslocamento de potencial para valores mais positivos à medida que aumenta o teor de cobalto no banho. A análise adimensional dos transientes potenciostáticos para cobalto, ferro e FeCo 1:1 e 1:10 indica processo de nucleação progressiva; já Fe-Co 1:5 segue a curva teórica para nucleação instantânea. A caracterização química e física dos eletrodepósitos mostra dependência entre a morfologia superficial e a composição do banho eletrolítico. Além disto, análises por EDX sugerem que a composição química dos eletrodepósitos foi sempre correspondente à composição do banho eletrolítico. Desta forma, é possível classificar estes processos como deposição regular.Fe-Co alloys were deposited and dissolved in the solution containing metallic ions and in the NH 4 Cl solution. Voltammetric results suggest interaction between the alloy components, constituting a solid solution. ALSV profiles show a differentiation for the dissolution process of the individual metals and alloys, with potentials displacement in the dissolution processes for more and more positive values, as the proportion of cobalt increases in the bath. The nondimensional analyses of the potentiostatic transients for the cobalt, iron and Fe-Co 1:1 and 1:10 suggest a progressive nucleation. However, Fe-Co 1:5 allowed instantaneous nucleation. The chemical and physical characterization of the electrodeposits showed dependence between the surface morphology and the composition of the electrolytic bath. Besides, EDX analyses showed that the composition of the electrodeposits were always corresponding the chemical composition of the electrolytic bath. In this way, it was possible to classify these processes as regular deposition. Keywords: electrodeposition, anodic dissolution, Fe-Co thin films IntroductionThe electrodeposition of alloys is a process much more complex than the electrodeposition of pure metals and several binary alloys systems have been investigated and reviewed. [1][2][3][4][5][6][7][8][9][10][11][12] Moreover, only few alloys systems have been industrially applied because an adequate control of these complex processes is naturally required in order obtaining a correct understanding of mechanisms. Electrodeposited alloys have potential applications for magnetic shielding, memory devices for computers and recording tapes, for corrosion protection and for electrocatalysis.Nowadays, the determination of alloy phase structure has been carried out using electrochemical techniques, such as galvanostatic and potentiostatic techniques, and, in most cases, anodic linear sweep voltammetry. 13 Literature on the electrodeposition of alloys of the iron group metals (Ni, Fe, Co and Zn...

Sonoelectrochemical (20 kHz) production of Co65Fe35 alloy nanoparticles from Aotani solutions

“…the formation of the binary Co-Fe alloy on Ti, starts at a discharge potential of -0.9 V vs. sce. This observation is in good agreement with literature [34]. In the anodic part of the voltammogram and in the potential range of [-0.5 V; +0.5 V vs. sce], the anodic peak potential on Ti, corresponding to the stripping of Co-Fe, is E pa,Ti = +80 mV vs. sce can be seen.…”

“…From our findings, it appears that it is not straight-forward to separate individual Co-Fe alloy nanoparticles due to both their magnetic properties [34] and their physical nature, i.e. the high surface energy that leads to aggregation (in order to minimize system energy).…”

“…In the potential range [+1.0 V; -1.5 V vs. sce], all voltammograms performed at several rotation speeds showed current loops (in the cathodic branches), again, indicating the three-dimensional (3D) nucleation of Co-Fe and subsequent grain growth [34]. In the cathodic part of the voltammograms no limiting currents were observed, indicating that the electro-reduction process of the binary Co-Fe alloy is not only diffusion-controlled but also kinetically-controlled.…”

“…Figure 2 shows a typical cyclic voltammogram obtained under silent conditions in the potential range [+1.0 V; -1.5 V vs. sce]. A current loop in the cathodic branch of the voltammogram is obtained, indicating the three-dimensional (3D) nucleation of Co-Fe and subsequent grain growth [34]. In the cathodic part of the voltammogram the electro-reduction of Co-Fe, i.e.…”

Cobalt electrodeposition onto highly oriented pyrolytic graphite (HOPG) electrode from ammonium sulfate solutions

“…Most of the Co electrodeposition studies have been performed onto carbon electrodes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and some others onto stainless steel, 18,19 gold, [20][21][22] nickel, 23 copper 24 and platinum 25 electrodes. Probably, carbon electrodes are the preferred substrates because they offer an inert surface in where it is possible to study the nucleation and growth process neglecting the metal-metal interaction.…”