ELECTRICAL PROPERTIES OF POLYCRYSTALLINE LiCrxCo1-xO2 STUDIED BY IMPEDANCE SPECTROSCPY

A. Bel Hadj Mohamed1, A. Mouhsen2*, H. R'mili1, N. Amdouni3, M. S. Haouat1

1 Laboratoire de Micro-ondes, Département de Physique, Faculté des Sciences de Tunis,

Université de TUNIS El Manar, Campus Universitaire, 2092 El Manar II, TUNISIE

2 Laboratoire d’Instrumentation et d’Analyse des matériaux, Département de Physique, Faculté des Sciences et Techniques de Settat, Université Hassan I, Morocco

3 Laboratoire de Chimie des Matériaux, Département de Chimie, Faculté des Sciences de Tunis, Université de TUNIS El Manar, Campus Universitaire, 2092 El Manar II, TUNISIE

* Corresponding author. E-mail : az.mouhsen@excite.fr

Received : 15 May 2001; revised version accepted 29 January 2002

Abstract

Charge transport behavior of the mixed-transition metal oxides is studied by using impedance spectroscopy measurements at room temperature from 5 Hz to 13 MHz. The dielectric response and the complex permittivity of these materials were determined for the chrome composition . The conductivity of these materials is found to be dependent on both frequency and chrome composition. The ac-conductivity shows a relaxation peak, which shifts toward lower frequencies with increasing chrome substitution. Also, the shape of this dielectric loss peak depends on the chrome composition.

This relaxation is attributed to the movement of small polarons in the bulk of the material and to the displacement of Li+ ions toward their equilibrium states after stopping excitation.

Keywords : Metal oxides; Ionic conduction; Permittivity and relaxation.

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