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Frequency-dependant dielectric characteristics and conductivity behavior of Sr1-x(Na0.5Bi0.5)xBi2Nb2O9 ceramics

Hana Naceur, AdelMegriche, Mohamed ElMaaoui

This study reports the frequency effect on the dielectric properties and electrical conductivity of Sr1"x(Na0.5Bi0.5)xBi2Nb2O9 (x = 0.0, 0.2, 0.5, 0.8 and 1.0) ceramics, at various temperatures.Astrong low frequency dielectric dispersionwas observed in these ceramics.The dielectric constant, the tangent loss and the ac electrical conductivitymeasured as function of frequency have been found to fit to the JonscherÂ’s dielectric dispersion relations. Electricalmeasurementswereinfluencedbytwomechanisms, polarization due to the carrier displacement in the lowfrequencyregion and the contribution fromthe lattice at high frequencies.The ac conductivitybehavior is due to the hopping of oxygen vacancies.Detailed analysis of impedance spectrumsuggested that the electrical properties are stronglyfrequencydependent.