Analysis of Fe(II)-Ni(II) Electrochemical Reduction Process and Electrodeposition of FeNi Films

Abstract

The effects of boric acid and ammonium sulfate on the electrochemical reduction process of Fe(II) Ni(II) were studied. A series of FeNi thin films were prepared by electrodeposition with different current density and Fe(II) concentration in solution. Linear sweep voltammetry (LSV) results show that the reduction current of Fe(II) is higher than that of Ni(II) at the same concentration of Fe(II) and Ni(II) as well as the same electrodeposition parameters. Adding H3BO3 to Fe(II) Ni(II) solution is beneficial to obtain brighter and compact coating, and adding (NH4)2SO4 is beneficial to obtain higher reduction current density. Energy dispersive X-Ray spectroscopy (EDS) results show that the current density has a significant and nonlinear effect on the Fe content in FeNi thin films. The highest Fe content is obtained at a current density of 25 A∙cm−2. SEM results show that the surface morphology of FeNi films is controlled by the content of Ni and Fe in the films. With increasing Fe content in the film, the morphology of the film changes from smooth and compact to spherical bulge and eventually to smooth again. X-ray diffraction (XRD) results show that the structure of FeNi films is controlled by the content of Ni and Fe in the film. With increasing of Fe content in the film, the structure of the film changes from FCC (111) phase dominant to BCC (110) phase dominant. The average grain size of FeNi films does not change with solution composition and current density. The results of magnetic properties show that the saturation magnetization Ms is proportional to the Fe content in the films, and the maximum value of Ms appears at the highest Fe content. The coercivity Hc is almost independent of Fe content in the films and does not change with solution composition and current density.