Electrical properties of Gd-modified Pb(SnTi)O₃ ferroelectric ceramics

The Polycrystalline samples of (Pb_1−x Gd _x )(Sn_0.45Ti_0.55)_1−x/4O₃ (PGST) (x = 0, 0.05, 0.07, 0.1) were prepared using a standard mixed-oxide method. The XRD and SEM studies of the samples reveal that PGST samples have tetragonal symmetry with uniform grain distribution. Measurements of dielectric constant, dielectric loss and ac electrical conductivity were made in a wide temperature (300–650 K) and frequency (100 Hz to 1 MHz) range. These materials undergo a ferroelectric–paraelectric phase transition at 569, 582, 598, and 603 K for x = 0, 0.05, 0.07, 0.1, respectively. The ferroelectric property of some samples at room temperature was confirmed through the study of hysteresis loops. The Cole–Cole plots (ε′′ vs. ε′) at 125 and 150 °C form semicircular arcs with the center lying underneath the abscissa, deviated from the ideal Debye relaxation model to some extent. In all the compounds, the slope of ln σ_ac ~ 1/T shows a distinct variation for temperature below 450, 450 K to T _c and for T > T _c. The room temperature ac conductivity at 10 kHz lies in the range of 10⁻⁵–10⁻⁶ (Ω⁻¹ m⁻¹).