Structural and Ferroelectric Properties of Complex Perovskites Pb_(1-x)Ba_x(Fe_1/2Ta_1/2)O₃ (x = 0.00, 0.05, 0.1, 0.15)

Abstract

We have synthesized the complex perovskite oxides Pb_(1-x)Ba_x(Fe_1/2Ta_1/2)O₃ (where x = 0.0, 0.05, 0.10 and 0.15) by two steps Coulombite precursor process in cubic phase and studied the effect of Ba substitution in Pb(Fe_1/2Ta_1/2)O₃ through the dielectric and ferroelectric properties in the frequency range from 100 Hz to 1 MHz and in the temperature range from 118 to 363 K. The temperature dependence of the dielectric constant at different frequencies gives diffuse peaks which have been attributed to the occurrence of relaxor ferroelectric behaviour in Pb_(1-x)Ba_x(Fe_1/2Ta_1/2)O₃. The magnitudes of ε′_m, the maximum value of dielectric constant and T_m, the temperature corresponding to ε′_m are decreased with an increase of Ba²⁺ ion in the materials. There is evidence of Vogel-Fulcher type relaxational freezing in the samples. The analysis of real and imaginary parts of the dielectric permittivity with frequency has been performed assuming a distribution of relaxation times as confirmed by Cole-Cole plots.

Keywords:

• Perovskite oxide
• relaxor
• lead barium iron tantalate
• Vogel-Fulcher