STUDIES OF DIELECTRIC RELAXATION AND AC CONDUCTIVITY BEHAVIOR IN LAMELLAR DOUBLE HYDROXIDE

Elmelouky Abderrahmane, Mortadi Abdelhadi, Elghaouti Chahid, Belghiti Mohammed, Reddad Elmoznine

Abstract


The frequency dependent dielectric and conductivity behavior of a Zn-Al layered double hydroxides (LDH), with Cl interlayer anion and with Zn/Al ratio R=2, have been studied. The formation of layered double hydroxides (LDH) and changes in the structural properties were investigated by x-ray diffraction (XRD), FTIR and ICP. Electric and dielectric properties were studied over a frequency range of [200Hz–1MHz] and in the temperature from 300K to 375K. These Studies show that the relaxation contribution is superimposed by electrode polarization effect. The appearance of peak for each temperature in the imaginary part of permittivity and modulus suggests the presence of relaxing dipoles in the layered double hydroxides.  On increase of temperature, the peak shifts towards higher frequency side suggesting the speed up the relaxation time. The variation of ac conductivity with frequency obeys Jonscher power law except a small deviation in the low frequency region due to electrode polarization effect. The dc conductivity increases with increase in temperature. The temperature dependence of the relaxation times for all samples showed Arrhenius behavior, from which the activation energy was derived.

Keywords


LDH; Anionic clay; Dielectric properties;Universal power law; spectroscopy impedance

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