Electrochemical deposition of Fe-Pd thin films with 30% at Pd

Ferromagnetic Shape Memory Alloys (FSMA) are smart materials able to change shape and size by rearrangement of the crystallographic variants as a response to an external magnetic field, and exhibiting reversible martensitic transformation. FePd alloys (Pd ~ 30% at) are interesting FSMA, and in the present work we present original results about the electrodeposition of Fe-Pd alloy films. Fe-Pd films were electrodeposited by using an aqueous solution containing Fe₂(SO₄)₃ and PdCl₂ as metallic ions sources, ammonium hydroxide and 5-sulfosalicylic acid as complexing agents. Composition of the films was analysed by means of Energy Dispersive Spectroscopy (EDS) and X-Ray Fluorescence (XRF). The crystallographic structure and the surface morphology of the sample were determined by X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM), respectively. The magnetic properties were assessed by Vibrating Sample Magnetometer (VSM). The influence of temperature, current density, electrolyte hydrodynamics, PdCl₂ and (NH₄)₂SO₄ concentration on the electrodeposited film quality and composition and on the current efficiency of the process were investigated. Either by increasing the electrolyte temperature or agitation, or by reducing the current density, an increase in Pd content in the alloy was observed. The Pd content in the film also showed a linear dependence on PdCl₂ concentration in the electrolyte. Improvement of the film quality were observed by increasing the (NH₄)₂SO₄ concentration, or reducing the current density. The deposition parameters were optimized in order to obtain electrodeposited films with Pd content around 30% at.