Fabrication and Magnetic Properties of Ni Nanospheres Encapsulated in a Fullerene-like Carbon

Abstract

A very simple, efficient, and economical synthetic technique, which produces fascinating fullerene-like Ni-C (graphitic) core-shell nanostructures at a relatively low temperature, is reported. The thermal dissociation of Ni acetylacetonate is carried out in a closed vessel cell (Swagelok) that was heated at 700 degrees C for 3 h. The encapsulation of ferromagnetic Ni nanospheres into the onion structured graphitic layers is obtained in a one-stage, single precursor reaction, without a catalyst, that possesses interesting magnetic properties. The magnetoresistance (MR) property of Ni nanospheres encapsulated in a fullerene-like carbon was measured, which shows large negative MR, of the order of 10%. The proposed mechanism for the formation of the Ni-C core-shell system is based on the segregation and the surface flux formed in the Ni and carbon particles during the reaction under autogenic pressure at elevated temperature.

The Thermal Decomposition of Three Magnetic Acetates at Their Autogenic Pressure Yields Different Products. Why?

“…Early results on a similar reaction of Ni(AcAc) 2 have been reported. [16] This publication extends this report and also includes a comparison between Fe II , Ni II , and Co II acetates, which yield different products. This manuscript also attempts to account for and explain the formation of different products.…”

Fabrication of magnetic nickel–tungsten–phosphorus particles by electroless deposition

“…Consequently, passivation layers might be needed to protect these materials. For instance, magnetic materials can be encapsulated in carbon to resolve this problem, but a higher process temperature is required with this method [8]. Besides, one family of the common passivation and magnetic materials used in industry is the electroless nickel-phosphorus (NiP) alloys and their derivatives [9].…”

Effects of a 10 T External Magnetic Field on the Thermal Decomposition of Fe, Ni, and Co Acetyl Acetonates

“…A similar effect of 10 T MF on the alignment of Co-C and Ni-C is anticipated. It is worth mentioning that without the MF, acetyl acetonates of Co, Ni, 23 and Fe produced completely core-shell morphologies of Co-C, Ni-C, and Fe 3 O 4 -C, respectively. In the control reactions, under a low MF (>1 T), we did not observe any changes in morphology, compared to 0 T MF.…”