Effect of titanium substitution on film structure and ferroelectric properties of Sr-deficient Sr0.75Bi2.35Ta2O9 thin films

Abstract

Ferroelectric films of bismuth-containing layered perovskite Sr0.75Bi2.35(Ta2-x,Ti-x)O-9 (x=0-0.8) have been prepared using a metal organic decomposition method. The effects of Ti substitution on the rnicrostructure evolution and ferroelectric properties of Sr0.75Bi2.35Ta2O9 films were investigated. A maximum remanent polarization of 2P(r)=30.7 muC/cm(2) was obtained for the Sr0.75Bi2.35Ta1.8Ti0.2O9 film as compared to Sr0.75Bi2.35Ta2O9 films (19.6 muC/cm(2)) annealed at 800 degreesC in air. The Ti substitution for Ta leads to charge compensation for the self-produced positive Bi-Sr(.), due to the occupation of Bi on Sr vacancies and is responsible for the increase in leakage resistance. The leakage current density as low as 2 X 10(-8) A/cm(2) can be obtained at an applied electric field of 100 kV/cm. Substitution of Ti for Ta shows a positive effect on the fatigue endurance of Sr-deficient Sr0.75Bi2.35Ta2O9 film. (C) 2002 Elsevier Science B.V. All rights reserved.