Effect of lanthanides-substituted on ferroelectric properties of bismuth titanate thin films prepared by metalorganic decomposition

The effect of lanthanides (A = La, Eu, Ce, Dy, Yb)-substitution on the ferroelectric properties of bismuth titanate (Bi3.25A0.75Ti3O12, BAT) thin films has been investigated. The structure and morphology of the films were analyzed using X-ray diffraction and scanning electron microscopy, respectively. After annealing at 700 °C, the BAT films exhibited a polycrystalline structure. As a increasing the ionic radius of the lanthanides element (Eu, Ce) with a smaller ionic radius than La in the pseudoperovskite layer, the BAT thin films showed well saturated P-E curves and the remanent polarization (2Pr) values increased from 8.08 and 44 μC/cm2 at an applied voltage of 10 V. The BAT thin films exhibited no significant degradation of switching charge at least up to 5 × 109 switching cycles at a frequency of 100 kHz. Moreover, the BAT film capacitors have appeared good retention properties after 3 × 104 s at room temperature.