Controlled electrochemical deposition of magnetostrictive Fe1 − xGax alloys

In this study, using steady-state electrochemistry at a rotating disk electrode, a deposition mechanism for giant magnetostrictive Fe1 − xGax alloys is proposed in which the formation of an adsorbed monovalent [Fe(I)]ads intermediate is determined to be the rate-determining step. In subsequent steps, this intermediate either gets reduced to iron or catalyzes the reduction of gallium by forming an adsorbed [Ga(III)–Fe(I)]ads intermediate. In line with the proposed mechanism, it was experimentally shown that the differences in the mass-transport rates of Fe(II) species determined the thin film composition. Therefore, this study has made possible a controllable and reproducible deposition of Fe1 − xGax thin films with compositions in the entire range of interest (15%–30% Ga). As-grown Fe80Ga20 thin films were found to have magnetostriction constants of ~ 112 ppm.

► Deposition mechanism involving a rate determining step is proposed for Fe1 − xGax alloys. ► Conditions for metallic Fe―Ga or non-metallic Fe―Ga-oxide phases experimentally obtained. ► Controllable and reproducible deposition demonstrated in 15%–30% Ga range. ► Saturation magnetostriction values of as-grown Fe80Ga20 thin films were measured to be ~ 112 ppm.