Structural, optical and ferroelectric behavior of pure BiFeO_3 thin films synthesized by the sol-gel method

摘要

In this paper, BiFeO_3 (BFO) thin films were synthesized by the sol-gel spin-coating technique followed by annealing at different temperatures. The effect of annealing temperature on structural, optical, dielectric and ferroelectric properties of BFO thin film has been investigated. Single phase polycrystalline BFO films are confirmed by X-ray diffraction patterns. A strong dependence of grain size and shape on annealing temperature was observed. The optical energy band gap values found decrease from 2.42 to 2.27 eV with raise annealing temperature from 500-600 ℃, respectively. The film annealed at 500 ℃ showed a well saturated polarization-electric field loop. The remnant polarization and saturation polarization values are decreased with increasing annealing temperature. The anomaly in temperature dependent dielectric permittivity was observed at magnetic transition point.