Parameters characterizing the charge state of dielectrics

Abstract

This paper presents three physical sources of the electric field in dielectrics: excess free volume charges with the distribution q v (x,y,z), free surface charges with the distribution q s (x,y,z) and frozen polarization state in the dielectric. They have a deciding influence on the parameters of the electret, in particular they determine the total lifetime of the electret and technical components made of it. The indeterminacy related to the mutual proportions of the spatial and surface charges was discussed: one can find an infinite number of distributions of surface q se (x,y,z) and spatial q ve (x,y,z) charges leading to the same distribution of the electric field E(x,y,z). A general case of electret was considered, where a coexistence of relaxation decay of frozen polarization and Maxwellian relaxation dependent on volume conductivity of the dielectric is assumed. An attempt to interpret the charge lifetime in real electrets was made.

Studies of the effect of temperature on charge accumulation in PVDF-PMMA double-layered thin films based on depolarization current measurements

“…It has already been reported the neutralization of space charges by ohmic conduction is absent in short-circuit TSDC but it can, still, be perceived in the air-gap double-layer system. [30][31][32] In air-gap TSDC of the double-layer, the destruction of interfacial charges occurs due to the internal fields present in the double-layered sample are inverted so that the neutralizing charges of opposite sign are carried to the interface by ohmic conduction which gives rise to g-peak which confirms from the calculated value of activation energy (i.e. 0.44-1.07 eV) because a higher energy is required to align the charge carriers and for their successive release from the trapping sites.…”

Electret-Nanopore Ionic Flux Generator

“…Ionic flux across the electret nanopore is expressed by the one-dimensional Nernst-Planck equation Eq. (2). Under conditions of negligible concentration gradient due to uniform salinity across the membrane, the primary driver of ionic flux is electret surface charge induced electroosmosis and Eq.…”

“…Electrets are semi-permanently charged or dipole polarized dielectric material generating surface electric fields typically fabricated through injection of excessive charge via particle accelerators or applied electric fields at elevated temperature in the case of dipole polarized electrets inducing asymmetric charge of a previously neutral material over an extended period of time [1,2]. Nanopores are molecular-scale channels that regulate molecular transport in membranes, in nature these are found in subcellular membranes of cells that function to regulate ionic flow such as ion channels establishing membrane potentials pivotal to nerve signal transmission.…”

Advanced Design of Fiber-Based Particulate Filters: Materials, Morphology, and Construction of Fibrous Assembly

“…The charges held in PP stay relatively longer, as they are inert to conductive molecules such as water. Such a dielectric material that retains electric charges is called an electret [ 35 , 36 ].…”