Anomalous low-frequency dispersion. Near direct current conductivity in disordered low-dimensional materials

Abstract

An interpretation of the anomalous low-frequency dispersion process is presented which is based on a cluster description of the structural ordering and fluctuation in carrier-dominated dielectrics. It is shown that this form of response occurs for systems of low spatial dimensionality and generates a sample-size-dependent conductivity. The relationship of the mechanism to that of power-law noise in electrical systems is identified and its structural interpretation explored. Particular features of hydrogen-bonded systems are described in which the dispersion is likely to be important in a biological context.

A strategy for achieving low percolation and high electrical conductivity in melt-blended polycarbonate (PC)/multiwall carbon nanotube (MWCNT) nanocomposites: Electrical and thermo-mechanical properties

“…The incorporation of nanofillers in the nanocomposites may increase the dielectric permittivity due to several factors, such as (i) the morphology of the polymer in the nanocomposites is changed in the presence of nanofillers, (ii) the large surface area and nano-sized nanofillers creates a large interaction zone with the neighbors in the polymer nanocomposites [2], (iii) the space charge distribution in the nanocomposites has been changed for the high electrical conductive nature of nano-sized nanofillers [8], and (iv) also changes the scattering mechanism of the nanocomposites. Dissado and Hill [40] explained the dielectric permittivity of the nanocomposites and stated that the value of the dielectric permittivity is high at low frequency region due to 'quasi-dc' conduction. Lewis [41] explained 'quasi-dc' conduction with the help of O'Konski's model [42] and a double layer approach.…”

Signs of low frequency dispersions in disordered binary dielectric mixtures (fifty–fifty)

“…The critical frequencies, ω c , for the anomalous low frequency dispersions are marked with arrows in the figures. Although, the change of the exponent of the power law is not large before and after ω c , as stated in the literature (Dissado and Hill 1984), including (i) extra phases in considered structures or (ii) using phases with low frequency dispersions or (iii) using a higher computation size than 16 × 16 might alter these exponents. The influence of topology on the observed low frequency dispersion behavior in the middle part of the responses is not that significant, however, on both sides of the frequency window, the responses are influenced by the considered lattice structures.…”

“…At the lowest possible frequencies, it is often observed that there is a transition of the exponent, αβ or a, from a low value at high frequencies to a higher value at low frequencies beyond a characteristic frequency ω c is passed (Jonscher 1983, Dissado andHill 1984). This phenomenon is called the 'anomalous' low frequency dispersion.…”

“…Therefore, the concentration of defects is critical in the sense that local field changes in the materials influences the electrical properties, such as, conductivity of materials that do not obey Ohm's law (Sorbello 1984) in the presence of the interaction of charge carriers with themselves and with the defects. The micro-structure of the considered medium affects the conductivity of the system depending on a length scale which is defined as the distance between the charge scatterer or defects (Dissado andHill 1984, Sorbello 1984). Moreover, similar length scales can also be defined as the variation of the dielectric permittivity in a continuous random dielectric (Mendelson and Schwacher 1984) and the variation of charge density or the electric field.…”

“…Consequently, the region R 3 ∪R 2 is the anomalous low frequency dispersion (Dissado and Hill 1984) which is then expressed by summations two power laws;…”