A study of random resistor-capacitor-diode networks to assess the electromagnetic properties of carbon nanotube filled polymers

We determined the frequency dependent effective permittivity of a large ternary network of randomly positioned resistors, capacitors, and diodes. A linear circuit analysis of such systems is shown to match the experimental dielectric response of single-walled carbon nanotube (SWCNT) filled polymers. This modeling method is able to reproduce the two most important features of SWCNT filled composites, i.e. the low frequency dispersion and dipolar relaxation. As a result of the modeling important physical conclusion proved by the experimental data was done: the low frequency behavior of SWCNT-filled polymer composites is mostly caused by the fraction of semiconducting SWCNTs

Microwave absorption properties of pyrolytic carbon nanofilm

Cite this article as: Kuzhir et al.: Microwave absorption properties of pyrolytic carbon nanofilm. Nanoscale Research Letters 2013 8:60.We analyzed the electromagnetic (EM) shielding effectiveness in the Ka band (26 to 37 GHz) of highly amorphous nanometrically thin pyrolytic carbon (PyC) films with lateral dimensions of 7.2 × 3.4 mm2, which consists of randomly oriented and intertwined graphene flakes with a typical size of a few nanometers. We discovered that the manufactured PyC films, whose thickness is thousand times less than the skin depth of conventional metals, provide a reasonably high EM attenuation. The latter is caused by absorption losses that can be as high as 38% to 20% in the microwave frequency range. Being semi-transparent in visible and infrared spectral ranges and highly conductive at room temperature, PyC films emerge as a promising material for manufacturing ultrathin microwave (e.g., Ka band) filters and shields

Highly luminescent and electrically conductive hybrid material

We proposed a highly luminescent and electrically conducting polymer composite material based on polylactide acid (PLA) polymer filled with reduced graphene oxide (RGO) or graphene oxide (GO) nanoplatelets covered by organic Eu(III) complexes tris-dibenzoylmethane mono-1,10-phenanthroline europium(III) [Eu(DBM)3Phen]. No Eu(DBM)3Phen luminescence quenching by RGO and GO nanoplatelets has been observed in emission decay. Partial luminescence intensity decrease is caused by graphene nanoplatelets absorption. Conductivity of the composite film is increased by more than five orders of magnitude as compared to the pure polymer. The proposed material is suitable for 3D printing technology and wide applications in optoelectronics

Microwave dielectric properties of tannin-based carbon foams

Dielectric analysis of tannin-based carbon foams with different pore sizes, produced at different densities, was carried out in wide microwave frequency range (8 GHz – 35 GHz). Both dielectric permittivity and electrical conductivity of carbon foams at 8 GHz, were high, i.e. more than 70 and close to 10 S/m respectively, and increased with carbon foams density according to power laws. High microwave complex dielectric permittivity values of carbon foams reported here, along with other valuable properties such as “green” origin, low price, lightness, chemical inertness, thermal stability and high conductivity in static regime, open new routes for producing effective electromagnetic shields and filters from tannin-based carbonaceous porous structures

Temperature induced modification of the mid-infrared response of single-walled carbon nanotubes

The temperature dependences of the absorbance spectra of thin free-standing single-walled carbon nanotube (SWCNT) films were studied in the infrared range (700–6200 cm^−1) while heating the air from 300 to 575 K. The observed temperature variation in the infrared absorbance spectra has been explained by two different physical factors. The first one is the strong temperature dependence of the conductivity of p-type doped semiconducting SWCNTs. The second one is the temperature dependence of electron relaxation time of intraband electron transitions in metallic SWCNTs. The possibility of the separation of contributions from the interband and intraband transitions to the infrared spectra of SWCNT films has been demonstrated

Conductive Luminescent Material Based on Polymer-Functionalized Graphene Composite

The synthesis of a new nanostructured supramolecular europium complex supported by graphene oxide (GO) as a structure-forming site is herein presented. The bonding of Eu ions to the GO surface is proven by energy dispersive X-ray spectroscopy and photoluminescence mapping, as well as scanning electron microscopy (SEM), spectroscopic, Fourier transform infrared spectroscopy, Raman, and luminescence measurements. Though GO is one of the ligands and absorbs light strongly, the energy transfer from GO to Eu ion is weak. The splitting of D-5(0)-> F-7(2) peak and three-component luminescence decay means that there are several emitting centers in this composite. The obtained data are the first proof of concept for a stable, highly luminescent, and electrically conductive hybrid nanocomposite based on polystyrene added with 2% (w/w) of the obtained Eu-GO complex. The simple and reliable proposed procedure is prone to be easily scaled up and open the route for the commercialization of this nanomaterial

Microwave dielectric properties of tannin-based carbon foams

Dielectric analysis of tannin-based carbon foams with different pore sizes, produced at different densities, was carried out in wide microwave frequency range (8 GHz – 35 GHz). Both dielectric permittivity and electrical conductivity of carbon foams at 8 GHz, were high, i.e. more than 70 and close to 10 S/m respectively, and increased with carbon foams density according to power laws. High microwave complex dielectric permittivity values of carbon foams reported here, along with other valuable properties such as “green” origin, low price, lightness, chemical inertness, thermal stability and high conductivity in static regime, open new routes for producing effective electromagnetic shields and filters from tannin-based carbonaceous porous structures

Copper nanoparticles decorated graphene nanoplatelets and composites with PEDOT:PSS

A facile and reliable synthesis route to Cu-graphene nanoplatelets (GNP) hybrid films has been developed. Cu nanoparticles of 13.7 ± 3.4 nm mean size were attached to few-layer graphene sheets. The obtained composite has good film forming properties and resistance of 380 Ω as compared to pure GNP, forming unstable and weakly conductive films. Introducing the GNP-CuNP nanofiller into the conducting polymer PEDOT:PSS leads to a more pronounced improvement of the conductivity of the latter compared to the case of using pure GNP. A simple way to produce a stable and highly conducting composite for manifold printable electronics applications is demonstrated