Electrochemical preparation of Ni-La alloys from the EMIC-EG eutectic-based ionic liquid

The electrodeposition behavior of Ni-La alloys was investigated in 1-ethyl-3-methylimidazolium chloride-ethylene glycol (EMIC-EG; 1:2-M ratio) eutectic-based ionic liquid containing 0.1 M NiCl2 and 0.2 M LaCl3. Cyclic voltammograms revealed that La could be co-deposited with Ni under the inducement of Ni(II) species in this solvent. The analysis of the chronoamperometric transients showed that, as with deposition of metal Ni, the co-deposition of Ni-La alloy on a glassy carbon electrode followed an instantaneous nucleation and three-dimensional growth controlled by diffusion. Galvanostatically deposited Ni-La alloys with different composition and morphology were characterized by inductively coupled plasma-atomic emission spectrometry (ICP-AES), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The current density and temperature were found to play an important role in controlling the composition and surface morphology of the resultant Ni-La alloys. The structure of these deposits depended on the La content. Alloys containing less than 4 at.% La could be indexed to a disordered face-centered cubic structure similar to pure Ni, whereas alloys containing about 9 at.% Ni were completely amorphous (metallic glass).