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 (Bi(3.25)A(0.75)Ti(3)O(12), 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 degrees 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 (2P(r)) values increased from 8.08 and 44 mu C/cm(2) at an applied voltage of 10 V. The BAT thin films exhibited no significant degradation of switching charge at least up to 5 x 10(9) switching cycles at a frequency of 100 kHz. Moreover, the BAT film capacitors have appeared good retention properties after 3 x 10(4) s at room temperature. (c) 2004 Elsevier B.V. All rights reserved.