Effect of boron/phosphorus-containing additives on electrodeposited CoNiFe soft magnetic thin films

CoNiFe, CoNiFeB and CoNiFeP soft magnetic thin films were prepared by cyclic voltammetry method. The morphologies, composition and structures were characterized by scanning electron microscope (SEM), energy-dispersive X-ray spectroscope (EDS) and X-ray diffractometer (XRD). The soft magnetic properties were investigated through vibrating sample magnetometer (VSM). The corrosion resistance was investigated through Tafel polarization and electrochemical impedance spectroscopic (EIS). The results show that all the electrodeposited CoNiFe, CoNiFeB and CoNiFeP films are mixtures of crystalline and amorphous phases, and high amount of boron/phosphorus-containing additives favors the formation of amorphous state. Nanostructure is obtained in CoNiFe and CoNiFeB films. The inclusion of boron causes the film more dense and also increases its corrosion resistance. Meanwhile, the inclusion of boron lowers its coercivity (Hc) from 851.48 A/m to 604.79 A/m, but the saturation magnetic flux density (Bs) is almost unchanged. However, the addition of phosphorus greatly increases the film particle size and decreases its corrosion stability. The coercivity (Hc) of CoNiFeP film is also highly increased to 12485.79 A/m, and its saturation magnetic flux density (Bs) is greatly decreased to 1.25 T.