Maxwell–Wagner–Sillars mechanism in the frequency dependence of electrical conductivity and dielectric permittivity of graphene-polymer nanocomposites

2017 ◽  
Vol 109 ◽  
pp. 42-50 ◽  
Author(s):  
Xiaodong Xia ◽  
Zheng Zhong ◽  
George J. Weng
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Permittivity ◽  
Frequency Dependence ◽  
Polymer Nanocomposites

Frequency Dependence of Electrorheological (ER) Effect and Its Relationship to Dielectric and Electrical Properties in Ba1-xSrxTiO3 Suspensions

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1443-1448 ◽  
Author(s):  
Yasuhito Misono ◽  
Shoichi Furukawa ◽  
Hitomi Yosinaga ◽  
Junko Sugiyama ◽  
Keishi Negita
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Dielectric Permittivity ◽  
Field Strength ◽  
Electric Field ◽  
Frequency Dependence ◽  
Applied Electric Field ◽  
Electrode Polarization ◽  
Low Frequencies ◽  
High Frequencies

Varying the electric field strength (E), the ER effect, the dielectric permittivity, and the electrical conductivity were simultaneously measured on the Ba 0.75 Sr 0.25 TiO 3 suspension. It was found that at high E the ER effect increased with the frequency (f), while at low E it once decreased and then increased with increase in f. At high E, the dielectric permittivity at low frequencies was much larger than that at high frequencies, indicating that an electrode polarization was formed as a result of accumulations of ions, which were dissociated from the liquid at high E, near the electrodes. This electrode polarization was further confirmed in the time dependence of the electrical conductivity after the electric field was switched on. From these results it is suggested that the E-dependent frequency dependence of the ER effect may be due to the electrode polarization, which causes larger shielding of the applied electric field at lower f while smaller shielding at higher f.

Nanotube Networks in Polymer Nanocomposites:  Rheology and Electrical Conductivity

2004 ◽  
Vol 37 (24) ◽  
pp. 9048-9055 ◽  
Author(s):  
Fangming Du ◽  
Robert C. Scogna ◽  
Wei Zhou ◽  
Stijn Brand ◽  
John E. Fischer ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Polymer Nanocomposites

Dual percolations of electrical conductivity and electromagnetic interference shielding in progressively agglomerated CNT/polymer nanocomposites

2021 ◽  
pp. 108128652110214
Author(s):  
Xiaodong Xia ◽  
George J. Weng
Keyword(s):  
Experimental Data ◽  
Electrical Conductivity ◽  
Carbon Nanotube ◽  
Percolation Threshold ◽  
Polymer Nanocomposites ◽  
Electromagnetic Interference ◽  
Effective Medium Theory ◽  
Scale Model ◽  
Shielding Effectiveness ◽  
Emi Shielding

Recent experiments have revealed two distinct percolation phenomena in carbon nanotube (CNT)/polymer nanocomposites: one is associated with the electrical conductivity and the other is with the electromagnetic interference (EMI) shielding. At present, however, no theories seem to exist that can simultaneously predict their percolation thresholds and the associated conductivity and EMI curves. In this work, we present an effective-medium theory with electrical and magnetic interface effects to calculate the overall conductivity of a generally agglomerated nanocomposite and invoke a solution to Maxwell’s equations to calculate the EMI shielding effectiveness. In this process, two complex quantities, the complex electrical conductivity and complex magnetic permeability, are adopted as the homogenization parameters, and a two-scale model with CNT-rich and CNT-poor regions is utilized to depict the progressive formation of CNT agglomeration. We demonstrated that there is indeed a clear existence of two separate percolative behaviors and showed that, consistent with the experimental data of poly-L-lactic acid (PLLA)/multi-walled carbon nanotube (MWCNT) nanocomposites, the electrical percolation threshold is lower than the EMI shielding percolation threshold. The predicted conductivity and EMI shielding curves are also in close agreement with experimental data. We further disclosed that the percolative behavior of EMI shielding in the overall CNT/polymer nanocomposite can be illustrated by the establishment of connective filler networks in the CNT-poor region. It is believed that the present research can provide directions for the design of CNT/polymer nanocomposites in the EMI shielding components.

Complex dielectric permittivity, electric modulus and electrical conductivity analysis of Au/Si3N4/p-GaAs (MOS) capacitor

2021 ◽  
Author(s):  
Sema Türkay ◽  
Adem Tataroğlu
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Permittivity ◽  
Electric Modulus ◽  
Arrhenius Equation ◽  
Rf Magnetron Sputtering ◽  
Oxide Semiconductor ◽  
Complex Dielectric Permittivity ◽  
Mos Capacitor ◽  
Universal Power Law ◽  
Complex Electrical Conductivity

AbstractRF magnetron sputtering was used to grow silicon nitride (Si3N4) thin film on GaAs substrate to form metal–oxide–semiconductor (MOS) capacitor. Complex dielectric permittivity (ε*), complex electric modulus (M*) and complex electrical conductivity (σ*) of the prepared Au/Si3N4/p-GaAs (MOS) capacitor were studied in detail. These parameters were calculated using admittance measurements performed in the range of 150 K-350 K and 50 kHz-1 MHz. It is found that the dielectric constant (ε′) and dielectric loss (ε″) value decrease with increasing frequency. However, as the temperature increases, the ε′ and ε″ increased. Ac conductivity (σac) was increased with increasing both temperature and frequency. The activation energy (Ea) was determined by Arrhenius equation. Besides, the frequency dependence of σac was analyzed by Jonscher’s universal power law (σac = Aωs). Thus, the value of the frequency exponent (s) were determined.

Effects of layered sediments on the guided wave in crosswell radar data

Geophysics ◽  
1999 ◽  
Vol 64 (6) ◽  
pp. 1698-1707 ◽  
Author(s):  
Karl J. Ellefsen
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Permittivity ◽  
Radar Data ◽  
Guided Wave ◽  
Sand Layer ◽  
Clay Layers ◽  
The Waves

To understand how layered sediments affect the guided wave in crosswell radar data, traces are calculated for a model representing a sand layer between two clay layers. A guided wave propagates if the wavelengths in the sand layer are similar to the thickness of the sand layer. The amplitude of the guided wave but not its initial traveltime is affected by the thickness of the sand layer. In contrast, both the amplitude and the initial traveltime are affected by the locations of the transmitting and receiving antennas, the electrical conductivity of the sand layer, and the dielectric permittivity of the sand layer. This permittivity can be estimated from the initial traveltime. The effects of the layering on the waves in these calculated traces also are observed in field traces, which were collected in layered sediments.

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