Preparation And The Doping Modification Of BiFeO₃ Thin Film

BiFeO3 with ferroelectric and antiferromagnetic orderings above room-temperature, large great of polarization and simple perovskite structure, had been extensively investigated in recent years. In this paper BiFeO3 thin films were fabricated by sol-gel method. Besides, the doping modification and its effect on its performance are studied. icrostructure structure of films were analyzed by XRD and FESEM. The amount of doping were determined, combined with the dielectric properties, ferroelectric properties and ferromagnetic properties of BiFeO3 thin films.The BiFe O3 thin films were prepared by sol-gel method, and the factors in the conditions of preparing BiFe O3 were studied. Firstly, under ethylene glycol monomethyl ether and glacial acetic acid as a solvent, the best condition synthesizing pure phase bismuth ferrite films were investigated. The results showed that: when annealing method bismuth ferrite films, the annealing temperature, annealing time, the number of layers were rapid annealing, 550 °C, 9min and 12 layer, respectively,the best crystallinity of BFO film was obtained.Then the La-doped bismuth ferrite films were studied. The results showed that the right amount of La-doped can change crystal structure of the films and reducing the grain size. 8% of La-doped had the largest remnant polarization. The Co-doped does not change the crystal structure of the film, but it could reduce the particle size. The Co-doped could improve significantly the ferromagnetic film, 8% of Co-doped could promote residual magnetization for 0.21 emu/g. In the condition of La-doped at the A site at doping conditions of 8%, the Co-doped was able to change the crystal structure of the film and could decrease the leakage current density of the films. The minimum leakage current density was 3.5×10-4 A/cm2. The largest remaining remnant polarization and magnetization of films were 4.04 μC/cm2 and 0.36 emu/g respectively, but due to the leakage current is large, the hysteresis loop film is still saturated. Under the condition of La-doped at the A site at doping conditions of 8% and Co-doped at the B site at doping conditions of 8%, Ba-doped could make the crystal structure of the film occur another change, and because of the lower leakage current of the films as opposed to co-doped of La and Co, a relatively the complete hysteresis loop was obtained, Maximum remanent polarization film and the residual magnetization respectively were 4.04 μC/cm2 and 0.36 emu/g.