Impedance spectroscopy study of relaxor ferroelectric PLZT thin films obtained by PLD and RF-PLD

Ac conductivity of (Pb0.67La0.22)(Zr0.2Ti0.8)O3 thin films has been investigated by impedance spectroscopy. Thin films have been grown by pulsed laser deposition (PLD) and by PLD assisted by radiofrequency discharge in oxygen. A cubic perovskite structure similar to that of the target has been found by XRD analysis. The ac conductivity of the films has been studied as a function of the frequency, ac driving field and dc bias field amplitudes. We found a power law dependence on frequency at short time scale (high frequencies) and/or low field amplitude, while at low frequencies and/or high field amplitude the dc conductivity contribution was dominant. Measurements at high dc field (up to 150 kV/cm) indicate that films grown by RF-PLD have the ac conductivity decreased by one order of magnitude with respect to PLD-grown films.