Structural, optical, magnetic, ferroelectric, and piezoelectric properties of (Pb,Ba)(Ti,Fe)O3 perovskites: A macroscopic and nanoscale properties approach

Single-phase Pb0.50Ba0.50Ti1-xFexO3 (PBTF) polycrystalline thin films with different Fe doping contents were prepared on Pt/Ti/SiO2/Si substrates using a chemical solution deposition method. The effects of doping on their structural, optical, magnetic, and electrical properties were studied via a multi-technique approach on different scales. A structural phase transition from tetragonal to pseudocubic was observed when the Fe content increased, resulting in tetragonality reduction of the thin films. Another consequence of the Fe content increase was the decrease in the optical band gap energy, probably induced by localized states within the forbidden gap of the PBTF thin films associated with structural disorder. The Fe addition also resulted in a gradual modification of the domain structure, as clearly observed by piezoresponse force microscopy. Two processes, a weakened distortion of the TiO6 sublattice and a decreased ferroelectric and piezoelectric response, were identified. At the macroscopic level, the ferroelectric properties of the films decreased with increasing Fe content, in good agreement with the nanoscale piezoresponse force microscopy data. Finally, a long-range magnetic order to ferromagnetism evolved by increasing the Fe doping content from x = 0.0 to 0.10.