Electric properties of Ni-C and Co-C core–shell nanoparticles in polymer matrix

Abstract

A number of the nanocarbon-metal Ni_x-C and Co₅₀-C core–shell structures were obtained from phenol-formaldehyde resin as a carbon precursor using a mechanochemical method and pyrolysis at 1034 °K. The morphology of the obtained core–shell structures was characterized by scanning electron microscopy. The magnetic hysteresis loops of Ni₂₅-C and Co₅₀-C core–shell structures were investigated by using a vibrating sample magnetometer. The work presents the results of investigations of electrical resistivity of nanocarbon-metal Ni_x-C and Co₅₀-C core–shell structures embedded in polyvinyl acetate (PVA). Electrophysical properties of the composite materials (CMs) have been studied in a wide temperature range: 77–293 K. It was found that morphology and composition (the content of the metal phase and its relation to the carbon phase) of Ni_x-C core–shell structures embedded in PVA influences the value of electrical resistivity, its temperature dependence ρ(Т) and δρ/ρ parameter of composites. The materials with the higher content of core–shell structures (Ni₇₅-C and Co₅₀-C) are characterized by the lower electrical resistivity, while the materials with the significant content of separate carbon phase in the form of nanotubes are characterized by the weaker ρ(Т) dependence.

Keywords:

• Carbon
• cobalt
• core–shell
• electrophysical properties
• mechanochemical method
• nickel

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article.