Effect of nitrogen doping on the electromagnetic properties of carbon nanotube-based composites

Abstract

Nitrogen-doped and pure carbon nanotube (CNT) based composites were fabricated for investigating their dielectric properties in static regime as well as electromagnetic response properties in microwave frequency range (K a -band). Two classes of host matrix-polystyrene and phosphate unfired ceramics-have been used for composites fabrication. The study reveals miscellaneous effect of nitrogen doping on the dielectric permittivity, dc conductivity and electromagnetic interference shielding efficiency of CNT-based composites, produced with both polymer and ceramic matrices. The high-frequency polarizability, estimated for different-length CNTs, and static polarizability, calculated for nitrogen-containing CNT models using a quantumchemical approach, show that this effect results from a decrease of the nanotube defect-free-length and deterioration of the polarizability with incorporation of nitrogen in pyridinic form. V

Nitrogen-doped carbon nanomaterials: To the mechanism of growth, electrical conductivity and application in catalysis

“…For example, when nitrogen content in single-walled CNTs was increased from 0.4 to 1.6 at.%, conductivity decreased from 1800 to 1000 S/cm [58]. N-CNTs-containing composites (4 at.% N) had a lower conductivity than undoped materials [59]. The authors supposed that nitrogen atoms in the pyridinelike state serve as the sites for dipole scattering and decrease defect-free-length of N-CNTs, thus suppressing conductivity of the nitrogen-doped carbon material.…”

Design of Carbon Nanotube-Based Broadband Radar Absorber for Ka-Band Frequency Range

“…A great number of investigations show that nanocarbon materials have excellent electromagnetic properties to be used for production of composite materials with controlled electromagnetic properties [10][11][12][13][14]. In the present paper, we use carbon nanotube-based composites to produce an effective broadband absorber for Ka-band region (26-37 GHz).…”

Gigahertz Dielectric Polarization of Substitutional Single Niobium Atoms in Defective Graphitic Layers

“…In addition to the interfacial polarization, the ðNbþNbCÞ= C composite presents another polarization at ∼16 GHz. The macroscopic dielectric polarization and loss are ascribed to the existence of permanent dipoles, which could also be achieved by heteroatom doping, for example, K-and Cadoped fullerenes at cryogenic temperature around ∼9 GHz [11,12], Li-=Ti-doped oxides at megahertz frequencies [27][28][29], and nitrogen-doped carbon nanotubes at nearinfrared frequencies [30,31]. To understand the formation of a permanent polarization center for single niobium atoms, Fig.…”