Electronic and defect processes in oxides. The polaron in action

Abstract

The basic processes involving space charge are charge localization (including trapping) and charge transport. These processes may be associated with energy localization. At the molecular scale, energy localization is an initiator of electrical breakdown and aging phenomena. At the mesoscopic scale, energy localization generates the damage observed macroscopically and is associated with discharge. Processes on one length scale determine behavior on another scale. Most applications concentrate on macroscopic space charge, yet processes on the atomic scale determine the build-up and consequences of space charge. In non-metals, one key concept is that of self-trapping (formation of small polarons). This survey discusses the phenomenon of self-trapping and its effects on charge transport, charge trapping, and the measurement of localized charges. Most examples will relate to oxides, including bulk transition metal oxides, oxide interfaces, thin layers of oxide on silicon, and laser-and radiation-induced charges in alumina. The paper also links some of the ideas to the outstanding problems in the generation of space charge, including contactcharging, tribocharging, and impact charging.

Role of fibre–matrix interface and fibre direction on dielectric behaviour of epoxy composites

“…If the local variation of the dielectric susceptibility (caused by point defects, distortion of lattice, extended defects, etc.) is sufficiently large, charges could be trapped in the lattice which will be distorted and polarised [1,7]. The charge and the associated charge of polarisation are called polaron [6].…”

Dependence on crystallographic orientation of trapping properties in a polished MgO single crystal

“…In this case, a mesoscopic analysis (grain structure, dislocation structure, etc.) is needed to study the trapping phenomenon [5]. From the physical point of view, the effect of disorder in a solid insulator is to produce localized states called Anderson states [6].…”

Analysis of electron transfer between electron irradiated metallic ball and insulators in vacuum: A specific alternative to the mirror method

“…7,8 Many characterization techniques are currently used to study the charge trapping on defects. 7,8 Many characterization techniques are currently used to study the charge trapping on defects.…”