Flower-like hierarchical nickel microstructures: Facile synthesis, growth mechanism, and their magnetic properties

Flower-like hierarchical nickel microstructures were prepared by a facile chemical reduction method requiring 4 h at temperature of 85 °C without any template or external magnetic field. Nickel (II) sulfate hexahydrate was used as nickel source and hydrazine hydrate acted as the reducing agent. XRD study confirmed the highly crystalline with face-centered cubic (fcc) phase. SEM images revealed that the individual flower-like microstructures have an average diameter of 1–2 μm and are composed of sword-like nanopetals growing radially from the core of the spherical particles. HRTEM image and SAED pattern of the single petal show that the lattice spacing is 0.203 nm corresponding to the (1 1 1) plane of fcc nickel and the growth orientation is along [0 1 1] direction. A rational formation process of nickel micro-flowers was proposed. Magnetic hysteresis measurements revealed that the hierarchical nickel microstructures possess ferromagnetic behavior with an enhanced coercivity value of about 203.3 Oe.