Structure and Properties of Preferential (110) Orientation BiFeO3 Thin Films by Sol-Gel Method.

Multiferroic materials, coexisting of ferroelectric, ferromagnetic and ferroelastic properties, possess potential applications in functional devices. BiFeO₃ (BFO) is a unique room temperature multiferroic material with high ferroelectric Curie temperature and Neel temperature. The BFO thin films were prepared on Si (111) substrate by sol-gel method in this paper. XRD analyses show that the thin films exhibit pure phase and preferred (100) orientation when annealing temperature is 500 °C. Field emission scanning electron microscopy shows that the crystallization degree of the films is getting better with the increase of annealing temperature. The thickness of the sample is about 400 nm. The hysteresis loop of BFO films annealing at 500 °C show 1.93 µC/cm² remnant polarizations. However, the hysteresis loop is not perfect, which may be caused by a large leakage current. The magnetic hysteresis loop of BFO films is tested as well, indicating that the BFO film is antiferromagnetic and the residual magnetization (Mr) and coercive field (Hc) of the BFO films were 0.054 emu/g and 1026.4 Oe, respectively. [ABSTRACT FROM AUTHOR]