Dielectric response of PLZT ceramics x/57/43 across ferroelectric-paraelectric phase transition

The dielectric properties of lead lanthanum zirconate titanate (PLZT) ceramics [Pb(Zr0.57Ti0.43)O-3 + x at% of La, x = 3, 5, 6, 10 and 12] have been measured in the frequency range 1 Hz-1 MHz using the vector impedance spectroscopy (VIS) at different temperatures. All the compositions show both non-dispersive and dispersive dielectric responses in different temperature regions. The non-dispersive region obeys the universal dielectric response. A low frequency (<1 kHz) relaxation phenomenon with a high value of distribution parameter 'h' (similar to 0.4 to 0.6) has been observed in all the compositions around the temperature corresponding to the maximum dielectric constant (T-m). The activation energies as calculated from the relaxation and d.c. conduction processes are comparable. The ferroelectric phase transition is diffuse in nature and broadening of the peak increases with La content.