Dielectric giant

Inagaki K, Terasaki I, Mori H, Mori T (2004) Large dielectric constant and giant nonlinear conduction in the organic conductor 0-(BEDT-TTF)2CsZn(SCN)4. J Phys Soc Jpn 73 3364-3369... 

The notion of homogeneity is not absolute all substances are inhomogeneous upon sufficiently close inspection. Thus, the description of the interaction of an electromagnetic wave with any medium by means of a spatially uniform dielectric function is ultimately statistical, and its validity requires that the constituents—whatever their nature—be small compared with the wavelength. It is for this reason that the optical properties of media usually considered to be homogeneous—pure liquids, for example—are adequately described to first approximation by a dielectric function. There is no sharp distinction between such molecular media and those composed of small particles each of which contains sufficiently many molecules that they can be individually assigned a bulk dielectric function we may consider the particles to be giant molecules with polarizabilities determined by their composition and shape. 

Earlier experiments [400,401] (see also Refs. 402 and 403) showed that hydrated colloidal particles are characterized by polarization whose nature is determined by spontaneous orientation of the polar molecules of water on the surface of particles leading to formation of the giant momentum P. The energy advantage of formation of P is shown in Ref. 404, which is in agreement with a detailed study of the dielectric anomalies in thin water layers conducted in Ref. 405. Spontaneous polarization of the monolayers of polar molecules is theoretically substantiated in Refs. [406,407]. 

Collective optical excitations, like surface plasmon-polaritons in partially-ordered metal nanoparticle arrays, tend to be spatially localized. The localization facilitates a giant increase of linear and nonlinear optical responses such as Raman scattering, enhancement of spontaneous emission rate, nonlinear absorption and refraction. In this paper the spectral manifestation of light localization into metal-dielectric nanocomposites i s s tudied i n t he visible. T he e ffect o f t he 1 ateral e lectrodynamic coupling on transmission/reflection optical spectra is investigated for planar silver nanoparticle arrays (random close-packed and polycrystalline quasiregular structures). Combined action of electron and photon confinements is demonstrated experimentally and considered theoretically for ID-photonic crystals consisted of a metal nanoparticle stratified array. 

Composite materials formed by nanometer-sized metal particles embedded in dielectrics have a growing interest o wing to the large values of fast optical Ken-susceptibility, whose real part is related to the intensity-dependent refractive index 2 [ ] Ion implantation has been shown to produce a high density of metal nanoparticles (MN) in glasses [2], The high-precipitate volume fraction and small size of MN leads to giant value of the [3]. This stimulates an interest in the use of ion implantation to fabricate nonlinear optical materials. 

The first work reported was done at the beginning of the eighties and dealt with polyacetylene. (CH)x has been characterised under different forms foam [32] iodine doped [33] AsFs doped [34] IrClg doped (which exhibits a giant dielectric constant) [35] encapsulated [36] cis and trans isomers [37] anisotropic [38]. The volution of the transport mechanism with doping level has been studied by measuring evolutions of Oj)c and (75.5 GHz with temperature [39]. An analysis based on the fibrillar structure of polyacetylene has been given. Recent works have been published, as in the case of n-doped polyacetylene [40]. 

H. A. Pohl, P. S. Vijayakumar, L. Dunn, and W. T. Ford, Stable Dielectrics with Giant Polarization, 1983 Annual Report IEEE. Conf. on Electrical Insulation and Dielectric Phenomena, p. 486. 

Finally, it is worth mentioning that a phenomenon analogous to the difference between the normal and giant flexoelectricity of calamitic and bent-core nematics, respectively, exists in crystals, ceramics and polymers too. The flexoelectric response (defined in Eq. (3.1)) of perovskite-type ferroelectrics, " of relaxor ferroelectric ceramics and polyvinylidene fluoride (PVDF) films are four orders of magnitude larger than the flexoelectricity of dielectric crystals. In those sohd ferroelectric materials the polarization induced by flexing is evidently of piezoelectric origin. 

Liu XQ, Wu YJ, Chen XM (2010) Giant dielectric response and polaronic hopping in charge-... 

Liu XQ, Wu SY, Chen XM, Zhu HY (2008) Giant dielectric response in two-dimensional charge-ordered nickelate ceramics. J Appl Phys 104 054114... 

Ni L, Chen XM (2007) Dielectric relaxations and formation mechanism of giant dielectric constant step in CaCu3Ti4Qi2 ceramics. Appl Phys Lett 91 122905... 

Batsanov SS, GavrilMn SM, Batsanov AS et al (2012) Giant dielectric permittivity of detonation-produced nanodiamond is caused by water. J Mater Chem 22 11166-11172 Nebel CE (2007) Surface-conducting diamond. Science 318 1391-1392... 

Apparently, a giant increase in dielectric constant of these nanocomposites with filler content can be interpreted in terms of the formation of many mini-capacitors in the polymer matrix. However, the dielectric loss of the nanocomposites increases markedly when their filler content reaches and above. This is because the nanotubes link to one to another to form a conducting path network. 

Whangbo, M.H. and Subramanian, M.A. (2005) Structural model of planar defects in CaCu3Ti40i2 exhibiting a giant dielectric constant. Chem. Mater., 18 (14), 3257-3250. 

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