Structural, dielectric and ferroelectric properties of BiFeO3–BiInO3 solid solution thin films obtained by sol-gel method

Abstract

The construction of phase boundaries is a well-known strategy to enhance the performances of ferroelectrics. In the present work, BiFeO3 and BiInO3 with attractive high Curie temperature of 830 °C and 600 °C were considered to reveal an unexplored phase boundary. (100-x)BiFeO3-xBiInO3 (x = 10, 20, 30, 40, 41, 50, 60, and 80) films, with thicknesses of approximately 289 nm, were obtained through industrial-scalable sol-gel method on Pt/Ti/SiO2/Si substrates. Complete solid solution can form between BiFeO3 and BiInO3, changing from rhombohedral to orthorhombic structure with the increase of BiInO3 content. The macroscopic dielectric, ferroelectric and piezoelectric properties of the thin films were systematically studied to understand the effect of the solid solution, with its phase diagram being proposed. A phase boundary near 60BiFeO3–40BiInO3 is formed with much superior polarization switch and piezoelectric response, of which the Curie temperature is as high as 470 °C. The results not only deepen the understanding of BiFeO3-based solid solutions, but also push forward potential applications of BiFeO3-based films in devices particularly for potential application at elevated temperature.