Synthesis of Size-Tunable Monodispersed Metallic Nickel Nanocrystals without Hot Injection

Abstract

Size-tunable monodispersed hierarchical metallic Ni nanocrystals (58-190 nm in diameter) have been prepared by the reduction of Ni 2+ with hexadecylamine under atmospheric pressure. The diameter of the particles could be tuned by simply changing the reaction time. The products were characterized with X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), energy-dispersive X-ray (EDX), and selected area electron diffraction (SAED) techniques. The reaction mechanism was proposed, and the relationships between the size, hierarchical surfaces and the magnetic properties have been investigated. The as-synthesized Ni crystals exhibit higher coercivities than the bulk metallic material owing to the reduced size and the hierarchical surface structure. The saturation magnetization (Ms) and the ratio of remanence to saturation (Mr/Ms) increased with increasing particle size.

Enhanced Thermal Conductivity and Viscosity of Nanodiamond-Nickel Nanocomposite Nanofluids

“…In the presence of the magnetic field, the non-magnetic particles act as voids and break the magnetic circuits resulting in the reduction of bulk magnetization with the increase void concentration. The total magnetization of the ND-Ni composite based on the sum of volume concentration of individual magnetizations is 3.9 emu/g, which corresponds to a bulk value of nickel weight percentage of ~16%; this result is in consonance with values reported in the literature for assemblies of magnetic/non-magnetic particles 43 . When the ND-Ni nanocomposite is dispersed in distilled water, it still shows good magnetic properties, as demonstrated by placing a magnet near to the glass beaker ( Fig.…”

FACILE AND LARGE-SCALE FABRICATION OF Ni NANOCHAINS BY A CHEMICAL REDUCTION METHOD WITH THE ASSISTANCE OF EXTERNAL MAGNETIC FIELD

“…27 The coercivity (H c ) of the Ni nanochains was 133.2 Oe, showing greatly enhanced coercivity compared to the value of bulk Ni (0.7 Oe). 28 It was also higher than those of micron-sized Ni dendritic crystals (77 Oe 12 ) and°owerlike Ni spheres composed of Ni nanoparticles (90 Oe). 29 It has been demonstrated that the magnetic metal nanostructures with shape anisotropy will possess high coercivity.…”

Magnetic-field-induced deposition to fabricate multifunctional nanostructured Co, Ni, and CoNi alloy films as catalysts, ferromagnetic and superhydrophobic materials

“…This gives us a hint that we can easily adjust the Ms of the film samples for different applications by changing the molar ratio of two elements. The coercivity of bulk Co and Ni is a few tens of Oe 18 and 0.7 Oe, 19 respectively. Compared with their bulk counterparts, the as-prepared Co and Ni films exhibited relatively large coercivity, especially in the perpendicular direction.…”