Ferroelectric and fatigue behavior of Pb(Zr0.52 Ti 0.48)O3/(Bi3.15Nd0.85)Ti 3O12 bilayered thin films

Abstract

Bilayered ferroelectric thin films consisting of Pb (Zr0.52 Ti0.48) O3 (PZT) and (Bi3.15 Nd0.85) Ti3 O12 (BNT) layers have been successfully fabricated via a synthesis route of combining sol-gel and rf sputtering. Both ferroelectric layers are well retained in both PZT/BNT and BNT/PZT bilayered films as suggested by x-ray diffraction and secondary ion mass spectroscopy analyses. Their ferroelectric and dielectric properties are largely dependent on the thicknesses of the constituent layers. An anomalous enhancement in polarization is demonstrated by the PZT/BNT bilayered thin film, whereby the switchable polarization increases dramatically upon > 106 cycles of polarization switching. The fatigue anomaly observed for the PZT/BNT bilayered thin film is related to the space charges that are accumulated at the interfaces in the heterolayered structure. By comparison, the BNT/PZT bilayered thin film exhibited better ferroelectric behavior than that of the PZT/BNT film where the P-E hysteresis loops were relatively well saturated with higher polarization. The BNT/PZT bilayered thin film also demonstrated a much improvement in fatigue behavior as compared to that of the single layer PZT film. © 2008 American Institute of Physics.