Synthesis of cobalt nanowires with high shape anisotropy and crystallinity

Abstract

Owning the high spontaneous magntization Ms, the Cobalt (Co) is known as one of the important 3d-transition metal elements used for developing soft magnetic materials. With the high value of Ms, Co should become an ideal hard magnetic material if it can be prepared in the form with a large shape anisotropy. This paper presents the results of synthesizing Co nanowires by reducting the carboxylate Co(II) precursor in the presence of RuCl3 functioned as a catalyst via the change of time in the solvothermal chemical process. The structure, morphology, and properties of the obtained Co nanowires were characterized by the X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM). The results revealed the great impacts of the solventhermal’s times and the reaction temperatures on the morphology and nucleations of Co nanowires. The prepared Co nanowires were well crystallized in the hexagonal close-packed (hcp) phase. The highest Ms value of prepared Co nanowires reached 166.9 emu/g by synthesizing at 225 oC for 20 hours. At 175 oC and for 20 hours, the prepared Co nanowire owns the best hard-magnetic performance characterized by the values of 164.3 emu/g and 2.97 kOe for Ms and iHc, respectively. With these results, in the next stage, the synthesized Co nanowires will be used in manufacturing free rare-earth permanent magnets. Keywords: cobalt nanowire, solvothermal, anisotropic shape, magnetic materials.