Microstructural studies of (PbLa)(ZrTi)O3 ceramics using complex impedance spectroscopy

Lanthanum modified lead zirconate titanate (PLZT:8/60/40) ceramics prepared by a sol-gel route showed a well-defined microstructure comprising of grains separated by boundaries. Complex impedance spectroscopy has provided a convincing evidence for the existence of both grain (bulk) and grain-boundary effects that were separated in the frequency domain in impedance spectrum. The impedance analysis further provided the value of relaxation frequency, which was a characteristic intrinsic property of the material and was independent of sample geometrical factors. Relaxation frequency calculated at different temperatures was used to evaluate bulk dielectric constant (epsilon(b)), which was compared with the real part of the dielectric constant (epsilon'). The temperature variation of the bulk electrical conductivity (sigma(dc)) indicated an evidence of Arrhenius-type thermally activated process showing a linear variation up to a temperature of 713degreesK and was predominantly governed by grain boundary conduction showing a plateau region beyond 713degreesK. (C) 2004 American Institute of Physics.