GROWTH OF NICKEL NANOSTRUCTURED BEADS AND THIN FILMS

Abstract

Ferromagnetic nickel metal beads, fibers, and thin films have been successfully grown from salt solution by a stepwise hydrazine reduction route with and without surfactants. XRD analyses showed that nickel was grown in the metallic phase and no other phases such as nickel oxide were detected in the prepared samples. SEM investigations showed that bead-like structures that agglomerated in the form of cloth- or net-like structures of about 1 μm size that composed of needle-like nanoparticles have been synthesized without using a surfactant. Sharp decrease in size was observed when sodium dodecyl benzene sulphonate (SDBS) and/or polyethylene glycol (PEG) were used. Bead-like morphology of nickel nanostructures of < 150 nm were deposited in this case. Free-standing nickel thin film structures that composed of needle-like nanoparticles of about 50 nm size were deposited by a stepwise reduction. Nickel nanostructures of < 100 nm showed higher coercivity (Hc) value of 184.6,Oe and lower saturation magnetization (Ms) value of 13.29 emu/g. This might be due to the anisotropic shape and size effects. It is strongly believed that nickel nanoparticles are self-assembled through a dipolar–dipolar interaction due to the magnetic property.