Dielectric relaxation in perovskite Ba(Zn1/2W1/2)O3

The complex perovskite oxide barium-zinc-tungstate, Ba(Zn1/2W1/2)O-3 (BZW) is synthesized by a solid-state reaction technique. The X-ray diffraction study of the sample at room temperature shows a monoclinic phase. The field dependence of dielectric response and the conductivity of the sample are measured in a frequency range from 100 Hz to I MHz and in a temperature range from 143 to 650 K. An analysis of the real and imaginary parts of the dielectric permittivity with frequency was carried out assuming a distribution of relaxation times as confirmed by Cole-Cole plot as well as the scaling behaviour of the dielectric loss spectra. The frequency dependent maxima in the imaginary impedance are found to obey an Arrhenius law with an activation energy similar or equal to 0.82 eV. The frequency dependent electrical data are also analyzed in the frame work of conductivity and electric modulus formalisms. The scaling behaviour of imaginary electric modulus shows the temperature independent nature of the relaxation mechanism. All these formalisms provided for qualitative similarities in the relaxation time. (c) 2007 Published by Elsevier B.V.