The effect of the annealing atmosphere on the properties of Sr2Bi4Ti5O18 ferroelectric thin films

The Sr2Bi4Ti5O18 (SBT-5) ferroelectric thin films were prepared on Pt/Ti/SiO2/Si substrate using the sol-gel method and annealing in oxygen, air, and nitrogen. Their properties were measured. After annealing in oxygen, the films showed good crystallization and a larger average grain size of approximately 34.05 nm. XPS analysis clearly showed that annealing in oxygen inhibited the generation of oxygen vacancies in the films, which contributed to the melioration of the ferroelectric properties. The remanent polarization was 20.09 mu C/cm(2) and the coercive field was 75 kV/cm. When the electric field was 15 kV/cm, the leakage current density was approximately 3.88 x 10(-7)A/cm(2), while the Ohmic conduction was the dominating leakage mechanism. Because the content of the oxygen vacancy in the samples annealed in oxygen atmosphere was lower, the fixing effect on the domain structure was weaker and the volume effect was not obvious, so the aging degree of the samples was low. The larger relative dielectric constant was 742, while the dielectric loss was 0.037 when the test frequency was 2.0 x 10(5) Hz.