Formation of Ni chains induced by self-generated magnetic field

Ultrafine chain-like Ni assemblies with a length of about 5 μm were successfully prepared by the reduction of Ni salts with hydrazine hydrate under normal pressure in the absence of any inorganic or organic templates. The resulting Ni chains were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the growth process of the Ni chains was investigated for the first time, using transmission electron microscopy (TEM) and XRD as well, which is valuable to study the self-assembly mechanism of magnetic nanocrystallites. Results indicated that the novel chain-like Ni assemblies were integrated from Ni microspheres with a diameter of about 250 nm. Magnetic hysteresis measurement revealed that the Ni chains showed ferromagnetic behavior with a saturation magnetization of 15.07 emu/g and a coercivity of 115.1 Oe at room temperature. It was supposed that the self-generated magnetic field could induce the formation of the Ni chains.