Effect of Ni/Fe ratio of electrolyte salts on the magnetic property of electrodeposited Fe–Ni alloy

Resumo

Electrodeposition of Fe–Ni thin films has been carried out on a copper substrate from simple as well as complex baths containing sulfate salts with Ni/Fe ratio of 1 : 1 and 12 : 1. Complex baths consistedeither all of ascorbic acid, citric acid and saccharine in addition to the salts viz. NiSO₄ · 7H₂O; FeSO₄ · 7H₂O; H₃BO₃ and Na₂SO₄ in simple bath. The chemical composition of the deposit was determined by an energy dispersive X-ray analyzer. Magnetic properties of the Fe–Ni films were measured by avibrating sample magnetometer (VSM). The X-ray diffraction was done on the electrodeposited thin films to determine Fe–Ni alloy phases. Magnetic properties of films were studied before and after heat treatment of the samples. It is found that the saturation magnetization decreases with increasing Ni content in the films obtained from simple baths with low Ni/Fe ratio (1 : 1) while the saturation magnetization increases with increasing Ni content obtained from complex bath with high Ni/Fe ratio (12 : 1). Among different baths with high Ni/Fe ratio of 12 : 1, the saturation magnetization of deposited film is higher deposited from a bath containing three complexing agents, namely, ascorbic acid, citric acid and saccharine than from a bath containing a single complexing agent–ascorbic acid. The ideal nature of the M_s–H (saturation magnetization vs. applied field) curve was obtained from complex baths with a high Ni/Fe ratio (12 : 1).