Soft magnetic properties of Ni–Cr and Co–Cr alloy thin films electrodeposited from aqueous solutions containing trivalent chromium ions and glycine

Abstract

Ferromagnetic Ni–Cr and Co–Cr alloy thin films were electrodeposited from aqueous solution containing trivalent chromium (Cr3+) ions and glycine. According to the Tafel slopes obtained from the cathode polarization curves for Ni–Cr and Co–Cr alloy deposition, it was estimated that Cr3+ ions inhibited Ni2+ and Co2+ ions from electrodepositing. Ni and Co preferentially electrodeposited rather than Cr and the electrodeposition process of Ni–Cr and Co–Cr was categorized to “normal co-deposition type.” At the cathode potential of −1.8 V versus Ag/AgCl/KCl sat., Ni—9.5 %Cr and Co—8.4 %Cr alloy deposits were obtained. X-ray diffraction patterns of the electrodeposits revealed that pure Ni and pure Co consist of large crystal grains, while Ni—9.5 %Cr and Co—8.4 %Cr alloys were composed of a solid solution phase with fine crystal grains. Magnetization of Ni—9.5 %Cr and Co—8.4 %Cr alloy thin films with fine crystalline phase reached to saturation at ca. 2.5 kOe in perpendicular direction to the film plane, while pure Ni and pure Co thin film with large crystal grains were hardly magnetized in the perpendicular direction. Soft magnetic properties were improved with increasing Cr content in the deposits.