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.
Isotropic magnetization response was demonstrated in electrodeposited nanocrystalline Ni-15%W alloy nanowire arrays, which can be applied to nanoscale magnetic field sensors. The Ni-W alloy nanowire arrays were electrochemically synthesized on a nanochannel template electrode from an aqueous electrolytic solution. X-ray and electron diffraction patterns revealed that Ni-15%W alloy deposits were composed of ultrafine crystal grains with a supersaturated solid solution phase. The magnetization of the Ni-15%W alloy thin films reached saturation at around 2.5 kOe in a perpendicular direction to the film plane, whereas the pure Ni thin films hardly magnetized in the perpendicular direction. On the contrary, Ni-15%W alloy nanowire arrays were easily magnetized, and reach saturation at around 1.0 kOe, even in a perpendicular direction to the array film plane that corresponds to the long axis direction of the alloy nanowires.
Abstract.To synthesize an array of numerous ferromagnetic nanowires, iron-group metals such as Ni, Co, Fe, Ni-Fe and Co-Fe alloys were electrodeposited from aqueous solution into a nanoporous template with numerical cylindrical nanochannels . The shape of nanowires was precisely transferred from the nanochannel template and the aspect ratio reached to around 150. Magnetic hysteresis loops revealed that Ni, Co and Fe nanowires were spontaneously magnetized to the long axis direction. Coercive force of the nanowires with 6000 nm in length was increased in decreasing the pore-diameter. The coercive force of Co nanowires with 40 nm in diameter has increased up to 1084 Oe.
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