Structure and Dielectric Relaxation Behaviour of [Pb_0.94Sr_0.06][(Mn_1/3Sb_2/3)_0.05 (Zr_0.49Ti_0.51)_0.95]O₃ Ceramics

Abstract

The field dependences of the dielectric response and conductivity are measured in a frequency range from 100 Hz to 1 MHz and in a temperature range from 300 K to about 775 K. The dielectric measurements (real and imaginary parts) of this composition with temperature (300 K - 775 K) at different frequencies (100 Hz - 1 MHz) unambiguously point towards relaxor behaviour of the material. The real part of the dielectric constant is found to decrease with increasing frequency at different temperatures while the position of dielectric loss peak shifts to higher frequencies with increasing temperature indicating a strong dispersion beyond the transition temperature, a feature known for relaxational systems such as dipole glasses. The frequency dependence of the loss peak obeys an Arrhenius law with activation energy of 0.15 eV. The distribution of relaxation times is confirmed by Cole-Cole plots as well as the scaling behavior of the imaginary part of the electric modulus. The frequency-dependent electrical data are also analyzed in the framework of the conductivity and modulus formalisms. Both these formalisms yield qualitative similarities in the relaxation times. The Rietveld analysis conforms that the materials exhibits tetragonal structure. The SEM photographs of the sintered specimens present the homogenous structures and well-grown grains with a sharp grain boundary.