Impedance spectroscopy of (Pb0.98La0.02)(Zr0.95Ti0.05)O3(PLZT-2/95/5) ceramics above ferroelectric phase transition temperatures

The complex impedance in PLZT-2/95/5 ceramic was measured over a temperature range of 30-600 °C at several frequencies. The capacitance anomaly of the phase transitions were observed near TL=96 °C and TU=214 °C. A remarkable diffuse capacitance anomaly behavior of complex capacitance was found between 300 and 600 °C. The complex impedance spectra above TU were fitted by the superposition of two Cole-Cole types of relaxations. The fast component in the higher-frequency region may be due to the ion migration in the bulk, and the slow component in the lower-frequency region is interpreted as the formation and migration of ions at the grain boundary or electrode/crystal interfacial polarization. We have found two different conduction mechanisms, which have different activation energies: E∼0.8 eV in the high frequency and E∼1.2 eV in the low-requency regions.