ELECTRICAL CHARACTERIZATION

OF THE FLUORIDE K3Fe5F15 BY IMPEDANCE SPECTROSCOPY

E. Hafidi1, Ma. El Omari1, A. Yacoubi1, Mo. El Omari1*, J. M. Réau2

1 Department of Chemistry, Faculty of Science, Moulay Ismaïl University, P.B.4010 Beni M’hamed, Meknes, Morocco

2 Institut de Chimie de la Matière Condensée de Bordeaux(I.C.M.C.B.), 87 Av. Dr. A. Schweitzer.33608 Pessac, France

* Corresponding author. E-mail : melomari@fsmek.ac.ma

Received : 30 November 2002; revised version accepted : 29 March 2003

Abstract

The ac response of the fluoride K3Fe5F15 has been investigated over the temperature range 293-773K using impedance spectroscopy. Impedance spectra show a curve that can be considered as an envelop of two depressed semicircles corresponding to bulk and grain boundary properties, and the modulus complex show two almost arcs. The d.c. measurements of this compound show an electronic conductivity. The equivalent circuit proposed to represent the electrical properties of the sample is determined by fitting the data by complex non-linear least squares immittance fitting program (LEVM). This circuit is constituted by series combination of two distributed-elements ZARC in parallel with series RC elements. Both distributed-elements ZARC represent the d.c. properties and the series RC elements represent the dielectric or ac response.

Keywords: Impedance spectroscopy; Equivalent circuit analysis; dc and ac conductivity,

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