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

Abstract

Abstract.Ferromagnetic Ni-Cr and Co-Cr alloy thin films were electrodeposited from aqueous solution containing trivalent chromium (Cr 3+ ) 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 Cr 3+ ions inhibited Ni 2+ and Co 2+ 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 vs.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.

Tuning the onset of ferromagnetism in heterogeneous bimetallic nanoparticles by gas phase doping

“…Lattice constants calculated from the (111) peak width indicate lattice expansion (3.52-3.55Å) compared to the Ni bulk value (3.51Å). Similar lattice expansion was also reported in bulk NiCr alloys [40], but the same was not clearly apparent in reported NiCr nanoparticles [7] or NiCr thin films [41] prepared by different growth methods for the given Ni/Cr compositions. The increase in lattice sizes can be ascribed to the larger atomic size of Cr (1.40Å) compared to that of Ni (1.35Å), and it indicates the presence of residual Cr inside the Ni core of the nanoparticles.…”

Effect of Growth Rate on the Crystal Orientation and Magnetization Performance of Cobalt Nanocrystal Arrays Electrodeposited from Aqueous Solution

“…In the potential range from −0.65 V to −1.50 V, the slope of the curve decreased with increasing cathodic overpotential. It is well known that the optimum cathode potential range for Co deposition can be determined by a cathodic polarization curve obtained in a wide cathode potential regime [ 29 ]. Considering the result obtained from Figure 4 , the optimum cathode potential range for Co deposition was determined to be less than −0.65 V.…”

CPP-GMR Performance of Electrochemically Synthesized Co/Cu Multilayered Nanowire Arrays with Extremely Large Aspect Ratio

“…−0.8 V. In this current density region, Cu 2+ ions diffusion seems to reach the limit. Furthermore, in the potential region, which is less-nobler than ECo eq , the cathode current density increases again at around −0.8 V. Generally, in an acidic aqueous solution, Co 2+ ions are reduced to metallic state in the process with large overpotential [26] due to the multi-step reduction process, which is proposed by Bockris et al [27]. Accordingly, this increase in the cathode current seems to correspond to an electrochemical reduction current of Co 2+ ions.…”