Effect of pH on the Structural Properties of Electrodeposited Nanocrystalline FeCo Films

In this paper, the effect of electrolyte pH on the composition and microstructure of FeCo films were investigated in details by using EDS, XRD and SEM. The composition of FeCo films is greatly affected by the electrolyte pH. With increasing temperature, the Fe content is increased while Co content is decreased. Low electrolyte pH (<= 3) favors the formation of fcc gamma phase while high electrolyte pH (4 and 5) leads to the formation of bcc alpha-Co7Fe3 phase in the studied films. High electrolyte pH results in a small decrease in the lattice parameter for the fcc phase and a small increase for that of bcc phase. With increasing pH value, the averaged grain sizes of fcc phase and bcc phase increase. The films prepared at low pH values (1 and 2) shows a very poor quality with rough surface. The surfaces of the films electrodeposited at high pH value (3 similar to 5) are generally quite smooth, uniform and compact. And porous and cracks can be observed in the FeCo films electrodeposited at high pH value (3 similar to 5).