Very Low Potential Electrodeposition of Sm-Co Nanostructures in Aqueous Medium Using Hard Templates

Abstract

Arrays of SmCo nanowires (NW) and nanotubes (NT) with a diameter of 200 nm and different lengths are synthesized by electrodeposition into the nanopores of an alumina membrane. The potential applied during the synthesis largely determines the nanostructure morphology, its crystallinity and composition. Potentials investigated are between −0.8 V and −3.0 V; in the potential range between −0.8 V and 1.0 V, long and perfectly ordered nanowires are obtained with a composition close to that of the equilibrium Sm 2 Co 17 phase in the binary alloy. For higher potentials, above −1 V, samples are nanotubes, 195 nm in external diameter and wall thickness of 30 nm with an equiatomical composition. Magnetic characterization reveals that all the nanostructures are soft ferromagnetic, with coercivity values below 60 mT. From the angular dependence of coercivity and the relative remanence it may concluded that in both, nanowires and nanotubes the magnetization reversal mechanism undergoes a transition from one at smaller angles, involving localized nucleation by curling, and further expansion of vortex-like domain walls. At higher angles, where the applied field is almost perpendicular to the NW/NT long axis, the mechanism changes to one involving nucleation by localized coherent rotation and further expansion of transverse Bloch-like walls.

Electrochemical Preparation of Cobalt-Samarium Nanoparticles in an Aprotic Ionic Liquid

“…[75][76][77][78] In the case of Sm 3d 5/2 , a peak was observed at 1084.0 eV, which was also slightly higher than metallic Sm (1081.0 eV) and Sm 2 O 3 (1083.5 eV). 42,45 Since the binding energy for contaminated carbon was identical to the literature value, the slight shift of the binding energies of Co and Sm indicated formation of the intermetallic compound of SmCo 7 . 42,[79][80][81][82] In addition, F and S assignable to TFSA − were detected by XPS, verifying the existence of TFSAin the sample.…”

“…42,45 Since the binding energy for contaminated carbon was identical to the literature value, the slight shift of the binding energies of Co and Sm indicated formation of the intermetallic compound of SmCo 7 . 42,[79][80][81][82] In addition, F and S assignable to TFSA − were detected by XPS, verifying the existence of TFSAin the sample. 82,83 The binding energy of the F 1 s peak at 689.5 eV was slightly higher than that observed for the ionic liquids, suggesting the TFSAin the sample interacts with the nanoparticles.…”

“…[19][20][21][22][23][24][25][26][27] Although the electrodeposition of RE-TM alloys from aqueous media is problematic due to the negative reduction potential of the RE elements (more negative than -2.3 V vs SHE), there are various reports on the production of the RE-TM alloys from aqueous media. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Besides, the preparation of RE-TM alloys from nonaqueous media has been attempted by many researchers. [45][46][47][48][49][50] For example, Gomez et al and Cojocaru et al investigated the electrodeposition of Co-Sm from a deep eutectic solvent (DES) based on choline chloride and urea (1ChCl:2U) at 70 °C.…”