Controllable synthesis of monodisperse polyhedral nickelnanocrystals

Abstract

Monodisperse polyhedral nickel nanoparticles composed of small nanocrystals have been successfully synthesized by a facile poly(N-vinyl-2-pyrrolidone) (PVP) mediated solution reduction process with hydrazine hydrate as the reducing agent. The phase structure, morphology and magnetic properties of the as-prepared products were extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). XRD pattern indicated that the as-synthesized products were nickel with well-crystallized facecentered cubic structure. SEM and TEM observations showed that the polyhedral nanoparticles consist of nanocrystals with size around 2 nm. The formation of these polyhedral nanoparticles is attributed to the oriented aggregation of nickel nanocrystals around a polymer-Ni 2+ complex framework structure. The magnetic property investigation shows that the polyhedral nickel nanoparticles exhibit a ferromagnetic behavior and possess a higher coercive field value than that of the bulk nickel.

Engineering the Spectrum of Dipole Field-Localized Spin-Wave Modes to Enable Spin-Torque Antidamping

“…Inset: Effective magnetization of the unsaturated Ni particle used at each external field to give the simulation results in Fig. 3(c), which agrees with the known hysteresis loop of a Ni particle [24]. The solid line is a linear fit, yielding 4πM Ni = 2.3H + 722.9 Gauss.…”

“…When I DC is applied, the effect of SHE-induced ST is maximized at 90 ○ , so measurements are performed at θ = 70 ○ to balance AMR and ST [7,9]. The low-coercivity [24] Ni particle is magnetized parallel to H ext , so the sample experiences a dipole field H d anti-parallel to H ext , creating a spatial field-well. Figs.…”

Facile design of a ZnO nanorod–Ni core–shell composite with dual peaks to tune its microwave absorption properties

“…Thus, the XRD results demonstrate the coexistence of ZnO and Ni. The following equations can be used to describe this synchronous reaction process: 34,35 Ni…”

Surfactant-assisted solvothermal synthesis of pure nickel submicron spheres with microwave-absorbing properties

“…Although the abovementioned Ni-based nanomaterials have been made, to our knowledge, there are only few reports on the synthesis of pure Ni nanoparticles. However, the successful routes for fabrication of the desired uniform architectures are usually complicated, which always involve the use of various surfactants and still give unstable assemblies with the small nanocrystal [ 30 ]. In addition, the metallic Ni nanoparticles are easily oxidized in the presence of nonmagnetic components [ 31 ].…”