Hydrogen Co-Deposition Induced Phase and Microstructure Evolution of Cobalt Nanowires Electrodeposited in Acidic Baths

Abstract

The growth and deposition mechanism of electrodeposited cobalt nanowires (NWs) at different bath temperatures (25°C–60°C) in strongly acidic bath (pH of 2.0) is studied. CV scans show that hydrogen co-deposition is most pronounced in 50°C bath. X-ray diffraction patterns of Co NWs show that a mixture of hcp and fcc phases grows at 25°C, (200) textured fcc-Co phase grows at 50°C, and (10true1̄0) and (11true2̄0) textured hcp-Co phase at 60°C, with these planes normal to the NW-axis. The magnetic properties studied by vibrating sample magnetometer show the change in coercivity, saturation field and magnetization reversal behavior is consistent with the phase of NW. Nucleation mechanism is explained on the basis of intermediates formation induced by the extent of hydrogen co-deposition leading to the change in nucleation overpotential and linked selection of the growth plane as per bath pH and temperature. Chronoamperometry study has confirmed the instantaneous and progressive growth mechanisms operative at 50°C and 60°C respectively and hydrogen co-deposition controlled grain size growth model is also put forth to understand the growth kinetics of fcc and hcp phase Co NWs. The suggested growth mechanism also consistently explains the growth in less acidic bath of pH 4.5.

Electrochemical Polymorphic Phase Formation in Metals

“…That cobalt forms the metastable -phase in electrodeposition at room temperature is an indication of an extremely rapid crystallization rate. The occurrence of this -form in cobalt deposits prepared electrochemically is confirmed by the literature [40][41][42][43][44]. Consequently, the existence of the metastable -form (typical of extremely rapid crystallization from a liquid state) in the cobalt prepared by electrodeposition is another proof of the phenomenon in point.…”

Effect of Pt doping on the preferred orientation enhancement in FeCo/SiO2 nanocomposite films

“…So a suitable non-magnetic matrix and a strong (200) FeCo texture are vital on improving FeCo soft magnetism and further applications. Our teams have devoted some years to investigating how to improve (200) FeCo texture growth 21 by choosing different metals as seedlayer or underlayer (Cu 22 , Co 23 and Al 24 ) and doping elements (Al 25 , Cu, Pt and Pd) into FeCo crystal lattice and also by choosing various preparing methods. Sol-gel technique is not only commonly easy-control to achieve uniform-doping among raw materials but also combines a superior advantage of low-cost.…”

Review—Electrochemical Phase Formation via a Supercooled Liquid State Stage: Metastable Structures and Intermediate Phases

“…The occurrence of this β-form in cobalt deposits prepared electrochemically is confirmed by the literature. [100][101][102][103] Consequently, the existence of the metastable γ-form or β-form (typical of extremely rapid crystallization from a liquid state) in the manganese or cobalt, respectively, prepared by electrodeposition was another proof of the phenomenon in point.…”