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

The dielectric behavior of (Sr0.4Ba0.6)0.925Bi0.05TiO3 (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 γ=1.6γ=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 TVF=188 K, Ea=0.0392Ea=0.0392 eV, and νo=2.98×1011νo=2.98×1011 Hz, further supports such a relaxor nature. The PP–EE hysteresis loop at different temperatures and ‘butterfly’ shape dc bias field dependence of permittivity at T>TmT>Tm (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 tgδtgδ are ∼2210∼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.