Effects of neodymium doping on microstructures and ferroelectric properties of bismuth titanate ferroelectric thin films

The Bi4-x Nd-x Ti-3 O-12 (x = 0.00, 0.30,0.45,0.75,0.85, 1.00,1.50) ferroelectric thin films were prepared on the Pt/Ti/ SiO2/Si(100) substrates using sol-gel method. The effect of neodynium doping on the microstructures and ferroelectric properties of films were studied. The experimental results show that Nd3+, only substitutes Bi3+, in the pseudo; perovskite block when Nd content x is lower than 0.45. When Nd content x is about 0.45, the film has the largest remnant polarization (2P(r)) of 32.7 mu C center dot cm(-2) at an applied field of about 270 kV center dot cm(-1). At x > 0.45, part of Nd ions are incorporated into the (Bi2O2)(2+) block, which would change the microstructure of (Bi-2 O-2)(2+) block and weaken its functions as the insulating layer and the space charge storage, resulting in the decrease of the 2 P,. When x = 1. 50, the dopout would destroy the structure of (Bi2 02)21 block, which leads to ferroelectric-paraelectric phase transition of the film.