Ferroelectric behavior of La and Mn co-doped BiFeO₃–PbTiO₃ thin films prepared by sol–gel method

Solid solution films of 0.7BiFeO₃–0.3PbTiO₃, 0.7(Bi_0.97La_0.03)FeO₃–0.3PbTiO₃, 0.7Bi(Fe_0.96Mn_0.04)O₃–0.3PbTiO₃ and 0.7(Bi_0.97La_0.03)(Fe_0.96Mn_0.04)O₃–0.3PbTiO₃ on Pt/Si structures were fabricated by sol–gel process. Effects of La and Mn doping on microstructures, ferroelectric behavior and leakage current of BiFeO₃–PbTiO₃ films were investigated. It was found that the coercive field of the BLFPT thin films obviously reduced, owing to the enhancement of domain reversal by the incorporation of La ions. In contrast, Mn-doped films prefer to exhibit the improved polarization and decreased leakage current density. In order to combine the advantages of the two elements’ doping, the films of binary elements co-substitution were successfully prepared. The La and Mn co-doped films demonstrated the best insulation compared with the other samples, which simultaneously achieved the optimized ferroelectric performance with the improved remnant polarization and reduced coercive field. The P _r and E _c values of co-doped BiFeO₃–PbTiO₃ thin films at room temperature were approximate 37 uC/cm² and 90 kV/cm, respectively.