Differences Observed in the Phase Structure, Grain Size–Shape, and Coercivity Field of Electrochemically Deposited Ni–Co Thin Films with Different Co Contents

Abstract

Nanostructured Ni–Co thin films were produced using galvanostatic electrodeposition on indium tin oxide (ITO)-coated glass substrates from an aqueous electrolyte solution without stirring at ambient temperature. Different compositions of the films were achieved depending on the Co ion concentration within the electrolyte. From the compositional analysis performed using energy dispersive X-ray (EDX) spectroscopy, the anomalous codeposition was found for all films and an increase in the Co content of the films was observed with increasing Co ion concentration within the electrolyte. The X-ray diffraction (XRD) analyses revealed that the phase structure of the electrodeposited Ni–Co thin films changes from single face-centered cubic (FCC) to a mixture of FCC and hexagonal close-packed (HCP) with the Co content within the films. It was also observed that the mean crystallite size estimated by applying the Scherrer method gradually decreases as the Co content within the films increases. The scanning electron microscopy (SEM) employed for the surface morphology showed that the size and shape of the grains formed on the film surface are strongly dependent on Co content within the films. Magnetic measurements performed by vibrating sample magnetometer (VSM) revealed that the films with different Co contents exhibit different magnetic properties; the Co-rich film has much higher coercivity field when compared with the Ni-rich film.