Grain boundaries and electrical properties of Bi0.85-xPr0.15DyxFe0.97Mn0.03O3 thin films

The chemical solution deposition route was employed to prepare Bi0.85-xPr0.15DyxFe0.97Mn0.03O3 (BPDyxFMO, x = 0.00, 0.04-0.07) thin films. The structure and the electrical properties were investigated. With doped Dy3+ ions, the coexisted two phases transform from the initial trigonal R3c: H structure and tetragonal P4 structure into trigonal R3c: H and R-3c: R structure. The grain sizes in BPDyxFMO thin films display a decreasing trend which indicates an increasing trend of the grain boundaries resistances. Meanwhile, an opposite trend between the grain boundaries resistance and the leakage current density appears because the resistance of grain boundaries blocks the leakage current. Due to multiple rare earth ions substitute for A-sites and single transition metal ions substitute for B-sites, the ferroelectricity of BPDyxFMO thin films deteriorates. At the same time, there will be aged ferroelectricties and broadened distributed switching fields. This is mainly attributed to the increasing grain boundaries and the formation of defects complexes which consist of positively charged defects and negatively charged defects. But more importantly, the Dy3+ has a positive effect on the magnetism. The saturation magnetization of Bi0.81Dy0.04Pr0.15Fe0.97Mn0.03O3 film is 2.39 emu/cm3.