Impedance spectroscopy studies on Fe3+ ion modified PLZT ceramics

Polycrystalline Fe3+-modified PLZT Pb0.92(La0.1Fe0.9)0.08(Zr0.60Ti0.40)0.98O3 (PLFZT) was prepared by high temperature solid-state reaction. Preliminary room temperature X-ray study confirms the formation of single-phase compounds in a tetragonal crystal system. The electrical behavior (complex impedance Z*, complex permittivity ɛ*, complex modulus M*) of the PLFZT system has been studied by non-destructive complex impedance spectroscopy (CIS). Grain and grain boundary conduction is observed from complex impedance spectrum at high temperatures (650 K and above) by the appearance of two semicircular arcs. The Cole–Cole plots of permittivity spectrum consisted of a circular arc followed by a semicircular spur indicate that the dielectric phenomenon of PLFZT is due to conductive grain boundaries. This is quite different in nature from Debye type mono dispersive phenomenon. The temperature variation of real permittivity gives evidence of the ferroelectric phase transition as well as of the relaxation behavior. The presence of non-Debye type multiple relaxations has been confirmed by complex modulus analysis.