Surfactant‐Assisted Synthesis and Characterization of Novel Chain‐Like CoNi Alloy Assemblies

Novel chain‐like CoNi alloy assemblies with a length of up to 6–7 μm were successfully prepared by a surfactant‐assisted hydrothermal synthetic route at 100 °C for 2 h. The individual submicrospheres built from smaller CoNi nanoparticles had a diameter of about 400–500 nm. These microspheres were then integrated to form the novel chain‐like CoNi alloy assemblies. The effects of synthetic parameters such as surfactant and solvent on the formation and morphology of CoNi samples were investigated. The experimental results showed that N2H4·H2O and CTA+ play important roles in the formation of the novel chain‐like CoNi alloy assemblies. Based on the structural information provided by X‐ray powder diffraction, scanning electron microscopy, transmission electron microscopy, selected‐area electron diffraction and energy‐dispersive X‐ray analysis, a growth mechanism was tentatively proposed for the formation of chain‐like CoNi alloy assemblies. Magnetic hysteresis measurement revealed that the chain‐like CoNi alloy assemblies display ferromagnetic behavior with a saturation magnetization of 96.15 emu/g and a coercivity of 144.75 Oe at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)