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Relationships between dielectric breakdown resistance and charge transport in alumina materials—Effects of the microstructure
- Source :
- Journal of the European Ceramic Society, Journal of the European Ceramic Society, Elsevier, 2007, 27 (2-3), pp.1193-1197. ⟨10.1016/j.jeurceramsoc.2006.05.047⟩
- Publication Year :
- 2007
- Publisher :
- Elsevier BV, 2007.
-
Abstract
- International audience; Dielectric breakdown is the main cause of insulator degradation. Breakdown strength strongly depends on materials microstructure (grain size, grain boundaries nature,...) [Liebault, J., Vallayer, J., Goeuriot, D., Tréheux D., Thévenot, F., How the trapping of charges can explain the dielectrics breakdown performance of alumina ceramics, J. Eur. Ceram. Soc., 2001, 21, 389–397; Si Ahmed, A., Kansy, J., Zarbout, K., Moya, G., Liebault, J., Goeuriot, D., Microstructural origin of the dielectric breakdown strength in alumina: a study by positron lifetime spectroscopy, J. Eur. Ceram. Soc., 2005, 25, 2813–2816]. The experimental study of these materials behaviour towards charge injection was performed by the scanning electron microscopy mirror effect (SEMME) method. It allows to measure the amount of injected charges finally trapped in the insulator. In order to explain the experimental results, we developed an iterative computer simulation of the self-consistent charge transport in bulk alumina samples during electron beam irradiation, based on a new flight-drift model (FDM). Ballistic and drift electron and hole transport as well as their recombination, trapping and detrapping (due to temperature and electric field) are taken into account. As a main result the time dependent secondary electron emission rate and the spatial distributions of currents, charges, field and potential are obtained. The analysis of these two kinds of results allowed us to identify the effect of the microstructure on the behaviour of the injected charges in the insulator and then to propose some mechanisms depending on the temperature leading to a good dielectric breakdown resistance. Indeed, at room temperature a huge localisation of charges limits further injection into the sample that permits to delay breakdown. On the other hand, when the temperature increases, the efficiency of the charge spreading behaviour is improved, leading to a higher dielectric breakdown strength.
- Subjects :
- 010302 applied physics
Materials science
Condensed matter physics
Dielectric strength
Interfaces
Insulator (electricity)
02 engineering and technology
Dielectric
Electron
021001 nanoscience & nanotechnology
Microstructure
01 natural sciences
Grain size
[SPI.MAT]Engineering Sciences [physics]/Materials
Grain boundaries
Dielectric properties
Electric field
Al2O3
0103 physical sciences
Materials Chemistry
Ceramics and Composites
Forensic engineering
Grain boundary
0210 nano-technology
Subjects
Details
- ISSN :
- 09552219
- Volume :
- 27
- Database :
- OpenAIRE
- Journal :
- Journal of the European Ceramic Society
- Accession number :
- edsair.doi.dedup.....5ba6bfff6df2692fcfa4e9565bd069f0