Enhanced Ferroelectric Properties of Gd- Substitution BiFeO₃ Thin Films Prepared by Sol-Gel Process

Abstract

BiFeO₃ and Bi_1−xGd_xFeO₃ (BGFO)(x = 0.05, 0.10, and 0.15) thin films were deposited on Pt/Ti/SiO₂/Si substrates by a sol–gel process. X-ray diffraction results show that a gradual phase transition from rhombohedral to pseudotetragonal structure may occur in BGFO films with the increase of Gd content. We observed a substantial increase in the remnant polarization (Pr) with Gd substitution and obtained a maximum value of 72.6 μC/cm² by 0.05 molar Gd incorporation. The leakage current behavior at room temperature of the films was studied and it was found that the leakage current density decreased from 10⁻⁶ to 10⁻⁹ A/cm² for 0.05 molar Gd-substituted films under a field 150 kV/cm. The reduction of dc leakage current of Gd -substituted films is explained on the basis of relative phase stability and improved microstructure of the material.

Keywords:

• Bi_1−xGd_xFeO₃ thin film
• X-ray methods
• Ferroclectric properties
• Sol–gel processes

Acknowledgments

The authors acknowledge the financial support from the National Natural Science Foundation of China (10874075) and the key Program of Hubei Province Education Committee under Grant No. D20082203.