Relaxor behavior of (Sr, Ba, Bi)TiO3 ferroelectric ceramic

The dielectric behavior of (Sr0.4Ba0.6)(0.925)Bi0.05TiO3 (SBBT) ceramic was investigated in the temperature range from 100 K to 450 K. Broad dielectric maxima, which shift to higher temperature with increasing frequency, and the value of the relaxation parameter gamma = 1.6-2 estimated from the linear fit of the modified Curie-Weiss law, indicated the relaxor nature of the SBBT ceramic. The dielectric relaxation which follows the Vogel-Fulcher relationship with T-VF = 188 K, E-a = 0.0392 eV, and v(o) = 2.98 x 10(11) Hz, further supports such a relaxor nature. The P-E hysteresis loop at different temperatures and 'butterfly' shape dc bias field dependence of permittivity at T > T-m (the temperature of permittivity maximum) signifies the occurrence of nanopolar clusters, which is the typical characteristic of relaxor ferroelectrics. At 300 K and 10 kHz, the dielectric constant and loss tg delta are similar to 2210 and 0.00118, respectively. The tunability (28%) and figure of merit (237) at room temperature show that the SBBT ceramic could be a promising candidate for tunable capacitor applications. (c) 2006 Elsevier Ltd. All rights reserved.