Research On Electrodeposition Of SmCo₅Alloy Films In Ionic Liquid And Their Properties

With the coming of the big-date era, Sm-Co magnetic films have broad development prospects for their outstanding performance in magnetic storage and stand out from thousands of magnetic materials. Electrodeposition is a simple, cost-effective method and is superior to the other preparations of Sm-Co magnetic films. Because of its stable performance and wide electrochemical window (more than6V), Reline ionic liquids is a kind of excellent electrochemical solvents.The reduction potential of Sm3+is very negative, and it is very difficult to achieve reduction in aqueous solutions. In this paper, we utilized the complexation between Reline ionic liquid and Co2+to induce the reduction potential of Sm3+shifting towards positive, and to achieve the purpose of codeposition. Constant current method and pulse-electrodeposition were selected to prepare Sm-Co magnetic films, single crystal silicon substrates were used as working electrodes. Samarium and cobalt contents of films prepared by constant current method could be controlled via regulating current density and salt-concentration in solutions. Composition of films prepared by pulse-electrodeposition also could be controlled, but by regulating pulse voltages, frequency and duty radios. Sm-Co thin films electrodeposited were amorphous and need annealing at1000℃, SmCo5alloy films could be prepared after annealing.Optimal growth crystal plane of SmCo5alloy films prepared by constant current method is (111) crystal face, average grain size is30nm, perpendicular coercivity is318.5Oe. Optimal growth crystal plane of SmCo5alloy films prepared by pulse-electrodeposition method is (002) crystal face, average grain size is20nm, perpendicular coercivity is483Oe. SmCo5shows hexagonal-CaCu5structure (c/a=0.81), c-axis direction is easy to be magnetized and perpendicular direction is hard to be magnetized. Coercivity of hard-magnetization direction is bigger than coercivity of easy-magnetization direction. The c-axis is perpendicular to (002) crystal face and with a35.1°angle to (111) crystal face, therefore,(002) crystal face shows a higher coercivity. Domain walls could not cross grain boundaries, thus, finer grain size is helpful to improve coercivity. SmCo5alloy films electrodeposited via pulse method had finer grains and higher coercivity than films prepared via constant current method.