FERROELECTRIC PROPERTIES OF Zr-DOPED Bi_3.25La_0.75Ti₃O₁₂ THIN FILM DEPOSITED BY RF MAGNETRON SPUTTERING

ABSTRACT

Thin films of Bi_3.25La_0.75Ti₃O₁₂ (BLT) and B-site substituted BLT by Zr, i.e. Bi_3.25La_0.75Ti_3−x Zr _x O₁₂ (BLTZx, x = 0.20, 0.50, 0.75, 1.00 and 1.50) were fabricated on Pt/TiO₂/SiO₂/Si substrates by RF magnetron sputtering method. Effect of Zr⁴⁺ amount on the microstructure and ferroelectric characteristics of the thin film BLTZx were investigated. X-ray diffraction shows that A-site La³⁺ and B-site Zr⁴⁺ co-substitution do not destroy the layered perovskite structure. Compared with the well-known BLT thin films, appropriate Zr⁴⁺ added, such as the BLTZ0.20 thin film, has larger remnant polarization (2Pr) and better fatigue resistance. However, with further increasing Zr⁴⁺-doping concentration, the remnant polarization (2Pr) tends to decrease. When x > 0.75 the remnant polarization become lower than that of BLT thin film. The remnant polarization (2Pr) of the BLTZx thin films under the 12 V were 17.8, 25.6, 22.4, 17.2, 11.6, 10.2 μC/cm², respectively, for x = 0, 0.20, 0.50, 0.75, 1.00 and 1.50, whereas there are almost no obvious difference in the Vc values.

Keywords:

• BLT
• Zr-doped
• RF magnetron sputtering
• fatigue

ACKNOWLEDGMENTS

This work is jointly supported by the Key program of National Nature Science Foundation of China (No. 90407023), Analytical and testing center of Huazhong University of Science and Technology.