Study of (Bi2O3)(BaxMo1-xO3) polycrystalline ceramic as relaxor ferroelectric

Solid solutions of bismuth layered (Bi2O3)(BaxMo1 - xO3) (0.2 <= x <= 0.8, x is in step of 0.2) ceramics were prepared by conventional solid-state reaction of the constitutive oxides at optimized temperatures with a view to study its electrical properties. Powder X-ray diffraction has been employed for physical characterization and an average grain size of similar to 16 to 22 nm was obtained. XRD study reveals the single phase structure of the samples. Dielectric properties such as dielectric constant (epsilon'), dielectric loss (tan delta) and ac electrical conductivity (sigma(ac)) of the prepared ceramics sintered at various temperatures in the frequency range 10(1)-10(7) Hz have been studied. A strong dispersion observed in the dielectric properties shows the relaxor type behavior of the ceramic. The presence of maxima in the dielectric permittivity spectra indicates the ferroelectric behavior of the samples. Impedance plots (Cole-Cole plots) at different frequencies and temperatures were used to analyze the electric behavior. The value of grain resistance increases with the increase in Ba ion concentration. The conductivity mechanism shows a frequency dependence, which can be ascribed to the space charge mainly due to the oxygen vacancies. The relaxation observed for the M '' (omega) or Z '' (omega) curves is correlated to both localized and long range conduction. A single 'master curve' for the normalized plots of all the modulus isotherms observed for a given composition indicates that the conductivity relaxation is temperature independent. (C) 2012 Elsevier B.V. All rights reserved.