ABSORPTION MECHANISMS OF MICROWAVES

AT HIGH TEMPERATURE IN PYROPHYLLITE

A. Mouhsen1*, J. L. Miane2, A. Khmou3, M. E. Achour3

1Département de Physique, Faculté des Sciences et Techniques, Université Hassan I, SETTAT, MAROC

2PIOM, ENSCPB, Avenue Pey-Berland, BP 108, 33402 TALENCE, France

3Département de Physique, Faculté des Sciences, Université Moulay Ismaïl, MEKNES, MAROC

* Corresponding author. E-mail : mouhsen2@ibnsina.uh1.ac.ma

Received 02 January 2001; revised version accepted 13 April 2001

Abstract

Permittivity measurements of ceramics as a function of frequency F and temperature T were made in the ranges 108 Hz < F < 4.109 Hz and 300 K < T < 900 K. From 600 K, we observe an increase of both the real and imaginary part of the permittivitty of the pyrophyllite ceramics. A simple model, involving an increase of the number of moving charges and dipoles resulting from the creation of vacancies, gives a good agreement with the observed variations.

From this model, we can estimate the activation energies of the two processes. The activation energy of the polarization process, associated with the creation of dipoles, is frequency independent and greater than the activation energy associated to the moving charged defects.

Keywords: Permittivity; Conductivity; Ceramics; Pyrophyllite; Polarization.

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