Effect of Additive Reagents in Plating Baths on Magnetic and Structural Properties of Soft Magnetic Films Prepared from Deep-Eutectic-Solvent-Based Baths

Abstract

Deep eutectic solvents (DESs), a kind of ionic liquids, are expected as a novel solvent for electroplating due to their unique properties such as low vapor pressure, non-combustibility, high thermal stability, and high conductivity. We have employed DES as a solvent to obtain soft magnetic Fe-Ni films and have reported that glycine is an effective bath additive to reduce the coercivity in Fe-rich Fe-Ni films. In the present study, we employed boric acid as an additive in the plating bath and investigated the effect of boric acid on the magnetic and structural properties of Fe-Ni films. The addition of the boric acid reduced the coercivity of the Fe-Ni films. In particular, the boric acid dramatically reduced the coercivity in Fe-poor films, and this behavior was quite different from that for the glycine. From the result of the TEM observation, we confirmed that the Fe-Ni films with low coercivity had a fine crystal structure, which suggested that the fine structure supported improving the soft magnetic properties.