Synthesis and Tunable Assembly of Spear-like Nickel Nanocrystallites: From Urchin-like Particles to Prickly Chains

Abstract

Urchin-like nickel particles and prickly nickel chains were selectively prepared by a facile low-temperature chemical reduction method at ambient conditions. The synthetic process involved the chemical reduction of nickel ions and the oriented growth of nickel nanocrystals under kinetic control independent of surfactants or external magnetic field. The branch length and the overall morphologies of the products could be tailored by properly tuning the process conditions and the component of the reaction solution. The magnetic properties of the products were studied as well and the results demonstrated that the products present ferromagnetic properties related to the corresponding microstructure. On the basis of a series of contrast experiments, the probable growth mechanism and fabrication process of the products were proposed. This work provided a facile and effective strategy to fabricate self-assembled nickel hierarchical structures with tunable morphologies.

Boric acid assisted electrosynthesis of hierarchical three-dimensional cobalt dendrites and microspheres

“…The coercivity depends on various types of anisotropy among which the shape anisotropy is very dominant and is of dipolar origin [53]. The higher coercivity of Co-dendrimers may be attributed to the shape anisotropy exhibited by cobalt [54]. The coercivity is inversely proportional to the diameter of the particles [55] and since both the dendrites and microspheres are aggregates, their coercivity values are nearly the same.…”

Polymer-directed synthesis and magnetic property of nanoparticles-assembled BiFeO3 microrods

“…The remarkable enhancement of coercive force can be ascribed to its unique one-dimensional chain-like structures. It is known that the coercive force of magnetic materials strongly depends on various types of anisotropy (crystal anisotropy, shape anisotropy, stress anisotropy, externally induced anisotropy, and exchange anisotropy), among which the shape anisotropy is predicted to produce the larger coercive forces [46,47].…”

Fabrication and magnetic properties of hierarchical nickel microwires with nanothorns

“…Similar to the gold or silver fcc crystals [20,21], the (111) plane of nickel also possess the lowest surface energy. Therefore, the growth of the nickel nanothorns was along the predominant direction paralleling to the (111) planes at proper reaction conditions [22,23]. With the prolonged reaction time, the prickly microspheres tended to join with each other to reduce both magnetic anisotropic energy and surface energy under the influence of the magnetic dipole interactions and the thermodynamic driving force.…”