Dielectric Spectroscopy Measurements of Relaxor Ferroelectric PLZT 9/65/35 Thin Films Obtained by RF Assisted PLD

Abstract

Dielectric relaxation measurements on Pb_1–x La_x(Zr_0.65Ti_0.35)_1–x/4O₃ with x = 0.09 (PLZT 9/65/35) thin films are presented. These films have been grown by pulsed laser deposition (PLD) assisted by radio frequency (RF) discharge in oxygen which allows to increase the plasma reactivity and to reduce the oxygen vacancies in films and at the film-bottom electrode interface.

The small signal dielectric constant and loss have been measured in the frequency range 100 Hz–1 MHz while temperature was varied between 300 K and 570 K. Dielectric permittivity vs. temperature variation was typical of relaxor ferroelectrics, with a broad peak that shifted towards lower temperature for lower driving signal frequency. The temperature of the dielectric maximum was close to that obtained in bulk (about 340 K) but the permittivity value was much lower. This was attributed to two causes: (i) the presence of small quantities of pyrochlore phase; (ii) a low permittivity interface layer. The room temperature permittivity showed a linear decrease with the logarithm of driving field frequency, indicating a dominating contribution from domain-wall pinning processes below transition temperature.

Keywords:

• PLZT
• thin films
• RF-PLD
• dielectric spectroscopy

Acknowledgements

Financial support from POLECER Network is gratefully acknowledged. Two of authors (MD and NS) gratefully acknowledge the financial support from Intergovernmental cooperation between Italy and Romania, theme 40.