Dielectric relaxation in Sr(Mg1/3Nb2/3)O3

The frequency-dependent dielectric dispersion of strontium-magnesium-niobate (SMN), Sr(Mg1/3Nb2/3)O-3 ceramic synthesized by the solid state reaction technique is investigated in the temperature range from 303 to 613 K The X-ray diffraction of the sample at room temperature (30 degrees C) shows monoclinic phase. The scanning electron micrograph of the sample shows the average grain size of SMN similar to 1 mu m. The frequency-dependent electrical data are also analyzed in the framework of the conductivity formalism. An analysis of the electric modulus and impedance with frequency is performed in the entire temperature range. The frequency-dependent maxima in the imaginary part of electric modulus are found to obey an Arrhenius law with activation energy similar to 1.8 eV. Such a value of activation energy suggests the existence of a relaxation mechanism (a conductive process), which may be interpreted by an ion hopping between neighbouring sites within the crystalline lattice. Results indicate that the relaxation mechanism of the material is temperature dependent and has dominated bulk contribution in different temperature ranges. The Cole-Cole approach is used to explain the relaxation mechanism in SMN. The scaling behaviour of imaginary part of electric modulus and imaginary impedance suggests that the relaxation describes the same mechanism at various temperatures. (C) 2008 Elsevier B.V. All rights reserved.