scholarly journals Dielectric response and percolation behavior of Ni–P(VDF–TrFE) nanocomposites

2017 ◽  
Vol 07 (03) ◽  
pp. 1750015 ◽  
Author(s):  
Lin Zhang ◽  
Patrick Bass ◽  
Guan Wang ◽  
Yang Tong ◽  
Zhuo Xu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Percolation Threshold ◽  
Polymer Matrix ◽  
Vinylidene Fluoride ◽  
Pressing Method ◽  
High Loss ◽  
Uniform Microstructure ◽  
Solution Cast ◽  
High Dielectric

Conductor–dielectric 0–3 nanocomposites using spherical nickel nanoparticles as filler and poly(vinylidene fluoride–trifluoroethylene) 70/30[Formula: see text]mol.% as matrix are prepared using a newly developed process that combines a solution cast and a hot-pressing method with a unique configuration and creates a uniform microstructure in the composites. The uniform microstructure results in a high percolation threshold [Formula: see text] ([Formula: see text] vol.%). The dielectric properties of the nanocomposites at different frequencies over a temperature range from [Formula: see text]70[Formula: see text]C to 135[Formula: see text]C are studied. The results indicate that the composites exhibit a lower electrical conductivity than the polymer matrix. It is found that the nanocomposites can exhibit an ultra-high dielectric constant, more than 1500 with a loss of about 1.0 at 1[Formula: see text]kHz, when the Ni content (53 vol.%) is close to percolation threshold. For the nanocomposites with 50 vol.% Ni particles, a dielectric constant more than 600 with a loss less than 0.2 is achieved. It is concluded that the loss including high loss is dominated by polarization process rather than the electrical conductivity. It is also found that the appearance of Ni particles has a strong influence on the crystallization process in the polymer matrix so that the polymer is converted from a typical ferroelectric to a relaxor ferroelectric. It is also demonstrated that the widely used relationship between the dielectric constant and the composition of the composites may not be valid.

Significantly enhanced dielectric response in composite of P(VDF-TrFE) and modified multi-walled carbon-nanotubes

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Jingwen Wang ◽  
Nan Wei ◽  
Fang Wang ◽  
Congcong Wu ◽  
Shuqin Li
Keyword(s):  
Carbon Nanotubes ◽  
Dielectric Constant ◽  
Percolation Threshold ◽  
Polymer Matrix ◽  
Vinylidene Fluoride ◽  
Volume Fraction ◽  
Poly Vinylidene Fluoride ◽  
Multi Walled Carbon Nanotubes ◽  
High Dielectric ◽  
Walled Carbon Nanotubes

AbstractTo develop a high dielectric constant composite of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] and multi-walled carbon-nanotubes (MWCNTs) with desirable homogeneity, MWCNTs were treated with a nitro-sulfuric acid by ultrasonication. Improvement of the dispersibility of chemically modified MWCNTs (a-MWCNTs) in polymer matrix, in comparison with that of unmodified MWCNTs in P(VDF-TrFE), was confirmed by field emission scanning electron microscopy (FESEM)-observed morphologies. Electric behavior of the composites with different volume fraction of dispersed carbon nanotubes phase can be described mainly by percolation theory. The percolation threshold (fc) of composites with a-MWCNTs (fc=0.0308) is larger than that of composites with MWCNTs (fc=0.0216) due to better dispersion of a-MWCNTs in polymer matrix and the reduction of aspect ratio of a-MWCNTs occurred in the modification procedure. The composite with 2.98 vol% (a volume fraction close to the percolation threshold) of a-MWCNTs has a dielectric constant of 592 at 100Hz and room temperature. The composite remains very flexible with an elastic modulus close to that of the parent copolymer.

New High-Dielectric-Constant Polymer-Ceramic Composites

2004 ◽  
Vol 847 ◽  
Author(s):  
Milind Arbatti ◽  
Xiaobing Shan ◽  
Z.-Y. Cheng
Keyword(s):  
Dielectric Constant ◽  
Vinylidene Fluoride ◽  
Ceramic Powder ◽  
Ceramic Composites ◽  
Flexible Composites ◽  
Giant Dielectric ◽  
Poly Vinylidene Fluoride ◽  
Solution Cast ◽  
Giant Dielectric Constant ◽  
High Dielectric

ABSTRACTA ceramic-powder polymer composite, making use of a newly developed ceramics - CaCu3Ti4O12 (CCTO) - that has a giant dielectric constant as the filler, is developed. In this work, poly(vinylidene fluoride - trifluoroethylene) [P(VDF-TrFE)] 55/45 mol% copolymer was used as matrix. It is found that the wettability between the copolymer and CCTO is poor, which makes the solution cast composites have a poor uniformity. The uniformity and thus the dielectric constant of the composites can be significantly improved by using hot-press technology to form “sandwich” structure. It is also found that the thermal annealing process can improve the dielectric constant of the composite. The experimental data show that for the flexible composites the dielectric constant at 1 kHz can reach more than 300 at room temperature and more than 700 at ∼70 °C.

Microstructural characterization of YBaCuO Films on LaAlO3 substrates

1989 ◽  
Vol 47 ◽  
pp. 180-181
Author(s):  
E. L. Hall ◽  
A. Mogro-Campero ◽  
N. Lewis ◽  
L. G. Turner
Keyword(s):  
Dielectric Constant ◽  
Single Crystal ◽  
Film Growth ◽  
Microstructural Characterization ◽  
Lattice Parameter ◽  
Film Plane ◽  
Substrate Material ◽  
High Loss ◽  
Amorphous Substrates ◽  
High Dielectric

There have been a large number of recent studies of the growth of Y-Ba-Cu-O thin films, and these studies have employed a variety of substrates and growth techniques. To date, the highest values of Tc and Jc have been found for films grown by sputtering or coevaporation on single-crystal SrTiO3 substrates, which produces a uniaxially-aligned film with the YBa2Cu3Ox c-axis normal to the film plane. Multilayer growth of films on the same substrate produces a triaxially-aligned film (regions of the film have their c-axis parallel to each of the three substrate <100> directions) with lower values of Jc. Growth of films on a variety of other polycrystalline or amorphous substrates produces randomly-oriented polycrystalline films with low Jc. Although single-crystal SrTiO3 thus produces the best results, this substrate material has a number of undesireable characteristics relative to electronic applications, including very high dielectric constant and a high loss tangent at microwave frequencies. Recently, Simon et al. have shown that LaAlO3 could be used as a substrate for YBaCuO film growth. This substrate is essentially a cubic perovskite with a lattice parameter of 0.3792nm (it has a slight rhombohedral distortion at room temperature) and this material exhibits much lower dielectric constant and microwave loss tangents than SrTiO3. It is also interesting from a film growth standpoint since it has a slightly smaller lattice parameter than YBa2Cu3Ox (a=0.382nm, b=c/3=0.389nm), while SrTiO3 is slightly larger (a=0.3905nm).

Fluoro-polymer functionalized graphene for flexible ferroelectric polymer-based high-k nanocomposites with suppressed dielectric loss and low percolation threshold

Nanoscale ◽  
2014 ◽  
Vol 6 (24) ◽  
pp. 14740-14753 ◽  
Author(s):  
Ke Yang ◽  
Xingyi Huang ◽  
Lijun Fang ◽  
Jinliang He ◽  
Pingkai Jiang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Percolation Threshold ◽  
High Dielectric Constant ◽  
Functionalized Graphene ◽  
Ferroelectric Polymer ◽  
Flexible Polymer ◽  
High K ◽  
High Dielectric

Fluoro-polymer functionalized graphene was synthesized for flexible polymer-based nanodielectrics. The resulting nanocomposites exhibit high dielectric constant, suppressed dielectric loss and low percolation threshold.

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