A simple method for forming amorphous rare earth-transition metal alloy nanotube arrays

Arrays of rare earth-transition metal alloy Co68Nd32 and Co96Sm4 nanotubes, with amorphous structures and outer diameters of ca. 270–330 nm and with lengths of over 30 μm, have been fabricated for the first time by direct current electrodeposition with a mercury cathode via anodic aluminum oxide (AAO) template. The using of mercury cathode is a crucial condition for the growth of nanotubes and the co-reduction of Co2+, Nd3+ and Sm3+ in aqueous solution without any chemical modification of the pores of AAO, since the liquid mercury has characters of excellent conductivity and fluidity, high surface tension, high photoelectric work function, and high over-potential. A possible growth mechanism for the nanotubes is proposed. The as-prepared nanotube arrays display low coercivity and uniaxial magnetic anisotropy, and the easy magnetization direction is perpendicular to the nanotubes axes.