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Journal of Materials Science

, Volume 29, Issue 24, pp 6473–6478 | Cite as

Electrical behaviour of compressed magnesia powder

  • D. S. Smith
  • R. Avedikian
  • P. Bourg
  • A. Laval
  • G. Nussbaum
  • J. M. Borie
Papers

Abstract

Magnesia powder has an important application for electrical insulation. In order to study the leakage conduction mechanisms, test samples were made by compressing 10 cm long alloy tubes filled with industrial class magnesia between a central electrode rod and the outer casing. The electrical behaviour between the central electrode rod and the outer casing was characterized up to 1200°C by measurement of the d.c. resistance and the frequency dependence of the a.c. impedance. Three regimes can be identified. Below 700°C, an activation energy of 1 eV is attributed to second phase(s) containing silicon and calcium which acts as a bypass. Above this temperature ionic conduction in the magnesia grains becomes predominant with an activation energy close to 2 eV. Finally, at even higher temperature above 1000°C, the activation energy increases further, indicating mixed ionic-electronic conduction. This last regime yields a voltage dependence to the resistance explained by blocking of the ionic component at the electrodes.

Keywords

Magnesia Activation Energy Ionic Conduction Material Processing Frequency Dependence 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • D. S. Smith
    • 1
  • R. Avedikian
    • 1
  • P. Bourg
    • 1
  • A. Laval
    • 2
  • G. Nussbaum
    • 2
  • J. M. Borie
    • 2
  1. 1.Laboratoire de Matériaux Céramiques et Traitements de SurfaceU.R.A. CNRS 320, Ecole Nationale Supérieure de Céramique IndustrielleLimogesFrance
  2. 2.Pechiney ElectrométallurgieLaboratoire Central de RechercheLe FayetFrance

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