Electrodeposition of Iron and Iron-Based Alloys from Ethylene Glycol Non-Aqueous Solutions

Iron and iron-alloys electrodeposition is considered a promising way for the fabrication of ferromagnetic thin films with tuned magnetic properties, especially for microfabrication industry [1]. Moreover, the use of iron as main component in magnets can reduce the material cost and toxicity. Film quality is highly dependent on contaminations, such as oxygen. Avoiding light-elements contaminations is nontrivial in the case of water-based solutions because of the formation of oxides/hydroxides at the working electrode due to local pH dependence, leading to poor magnetic performances. Thus, organic systems may represent a good alternative to traditional baths. Non-aqueous solutions based on ethylene glycol have been already reported for electrodeposition of iron [2], where the low chlorides content led to a compact and pure films. Several other approaches, based on DESs and Ionic Liquids, are present in literature [3], [4]. The low coercivity of ≈20 Oe showed in the previous work can thus be tailored with the addition of other metals or non-metals as alloying elements. This kind of materials are commonly obtained by metallurgy or sintering, with the strong limitations in terms of thickness and device integration. Iron co-deposition were investigated by means of the traditional electrochemical characterization, cyclic voltammetry (CV) and linear sweep voltammetry (LSV), and with more practical tools such as Hull cell. The films were deposited by means of potentiostatic and galvanostatic depositions, showing the dependence between experimental conditions and film composition (XRF). Results in in terms of morphology (SEM), composition/purity (EDX), microstructure (XRD) and magnetic properties (VSM) are shown. [1] B. Y. Yoo, S. C. Hernandez, D. Y. Park, and N. V. Myung, “Electrodeposition of FeCoNi thin films for magnetic-MEMS devices,” Electrochim. Acta, vol. 51, no. 28, pp. 6346–6352, 2006. [2] G. Panzeri, A. Accogli, E. Gibertini, C. Rinaldi, L. Nobili, and L. Magagnin, “Electrodeposition of high-purity nanostructured iron films from Fe(II) and Fe(III) non-aqueous solutions based on ethylene glycol,” Electrochim. Acta, no. Ii, 2018. [3] A. P. Abbott and K. J. McKenzie, “Application of ionic liquids to the electrodeposition of metals,” Phys. Chem. Chem. Phys., vol. 8, no. 37, p. 4265, 2006. [4] T. Welton, “Room-Temperature Ionic Liquids. Solvents for Synthesis and Catalysis,” Chem. Rev., vol. 99, no. 8, pp. 2071–2084, 1999.