Space charge in dielectrics. Energy storage and transfer dynamics from atomistic to macroscopic scale

The consequence of the coupling of a charged particle with a polarization field is the formation of a quasi-particle called the 'polaron'. The degree of 'localization' of such charge depends on the nature of this coupling. In this way, trapping at an atomic scale is described as...

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Bibliographic Details
Published in:IEEE transactions on dielectrics and electrical insulation 1998-10, Vol.5 (5), p.779-808
Main Authors: Blaise, G., Sarjeant, W.J.
Format: Article
Language:English
Subjects:
Aging
Dielectric materials
Dielectric thin films
Electric breakdown
Electron traps
Energy storage
Lattices
Physics
Polarization
Space charge
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Summary:The consequence of the coupling of a charged particle with a polarization field is the formation of a quasi-particle called the 'polaron'. The degree of 'localization' of such charge depends on the nature of this coupling. In this way, trapping at an atomic scale is described as resulting from the evolution of a coupling involving successively: the electronic polarization field, the infrared polarization field, and the quasi-static ionic polarization field. The internal energy stored in the surrounding medium polarized by the charge is high because the charge is so well localized. The maximum of this energy is obtained for the quasi-static polarization field; its magnitude is of the order of 5 to 10 eV per trapped charge. This work addresses the physics of aging and of the breakdown process on the basis of an unsustainable increase in local internal energy within the material, due to charge trapping-the polarization around a trapped charge increases the local energy; the relaxation of the material lattice then follows a rapid detrapping of charges from their sites, releasing the local excess site region energy into the material. Such a release executes transient virtual work on the material, producing macroscopic dielectric damage, and when critical, unstable conditions are achieved in the time domain, this is followed by electrical breakdown. This interpretation of electrical material breakdown is related to bulk breakdown as observed in thin film laminate structures (/spl sim//spl mu/m) and surface flashover as seen in large structures (/spl sim/mm to cm).
ISSN:1070-9878
1558-4135
DOI:10.1109/94.729703