High permittivity from defective carbon-coated Cu nanocapsules

Abstract

Carbon-coated Cu [Cu(C)] nanocapsules were prepared by a DC arc discharge method in a methane(CH4) atmosphere, and characterized by x-ray diffraction (XRD), thermal gravimetric analysis(TGA), scanning differential thermal analysis (SDTA), transmission electron microscopy(TEM) and Raman spectroscopy. The results show that the as-made product consists ofcarbon-coated Cu nanocapsules and giant onion-like fullerenes (GOLFs) in the diameterrange of 20–50 nm. The graphite outer shells effectively protect the Cu cores fromenvironmental oxidation, and have a greater defect density in comparison withbulk graphite and carbon nanotubes (CNTs). Its relatively complex permittivity(εr = ε′+iε′′) is also measured at 2–18 GHz. The values ofε′ and ε′′ reach 14.5 and 4.1, respectively, exhibiting excellent electromagnetic wave loss ability.