Induced Codeposition of Sm–Co Amorphous Films in Urea Melt and Their Magnetism

Abstract

The electroreduction of Co(II) and in urea–acetamide–NaBr– melts were investigated by cyclic volatmmetry and chronoamperometry. The reduction of Co(II) is an irreversible process. Sm(III) cannot be reduced alone, but Sm–Co can be codeposited by induced deposition. The mechanism may involve a polynuclear complex containing Co(II) and Sm(III). An amorphous Sm–Co film comprised of nanoagglomerates has been synthesized. SEM shows that most of the agglomerates fall within a size range of 20–35 nm with a few agglomerates in the 50–90 nm range. The Sm content in the films varies from 7.9 to 79.16 wt % with the applied potential and the molar ratio of in melt. The film could be crystallized by heat-treatment at 900°C. Large crystal grains appeared after heat-treatment and their phase was confirmed as . In addition, crystalline nanoparticles with the size of 10 nm were found on these large crystal grains. The magnetic properties of the Sm–Co films were determined using hysteresis loops, the coercive field of Sm (79.16 wt %)–Co amorphous film is 2300 Oe at 5 K; and the remanent magnetization and the saturation magnetization are 0.536 and , respectively.