3-D flower-like NiCo alloy nano/microstructures grown by a surfactant-assisted solvothermal process

Abstract

Uniform 3-D flower-like NiCo crystalline nano/microstructures were synthesized by a surfactant-assisted solvothermal process at 120 °C for 10–15 h, which were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometry (VSM). The effects of synthetic parameters such as surfactant, solvent and molar ratio of metal ions on the formation and morphology of NiCo samples were investigated. The experimental results showed that sodium dodecylbenzenesulfonate (SDBS) and solvent ethanol play critical roles in the formation of novel flower-like NiCo alloy assemblies, and the self-assembly evolution was found to be a two-stage growth process. Magnetic hysteresis measurements revealed that the flower-like Ni₄₈Co₅₂ alloy spheres with an average diameter of ca. 800 nm and hierarchical flower-like Ni₄₇Co₅₃ alloys with a size of ca. 5 μm display ferromagnetic behaviors with saturation magnetizations of 111.33 emu g⁻¹ and 103.58 emu g⁻¹, and coercivities of 84.27 Oe and 52.71 Oe, respectively, at room temperature.