Outstanding Ferroelectricity in Sol-Gel-Derived Polycrystalline BiFeO3 Films within a Wide Thickness Range

Collaborative Optimization of Curie Temperature and Piezoelectricity in Ternary BiFeO3-BiScO3-PbTiO3

The enhancement of piezoelectricity without compromising the Curie temperature of a piezoelectric is challenging due to phenomenological incompatibility. In the present work, the phase diagram of (0.68-x)BiFeO3-xBiScO3-0.32PbTiO3, with varied addition of BiScO3 (x = 0, 0.05, 0.10, 0.15, and 0.20), was constructed through systematic studies of the dielectric, ferroelectric, and piezoelectric properties. A rhombohedral-tetragonal phase boundary was observed near x = 0.10 BiScO3 addition, of which the piezoelectricity was found to be seven times larger than that without BiScO3 (∼208 pm/V vs ∼38 pm/V). Most importantly, a high Curie temperature of 430 °C is successfully inherited from binary 0.68BiFeO3-0.32PbTiO3. This is explained by optimized Bi compensation, which is observed critical regulating Curie temperature in BFO-based binary and ternary systems. These results open up a paradigm for collaboratively optimizing the Curie temperature and piezoelectric response for a number of ferroelectrics and provide a promising BiFeO3-BiScO3-PbTiO3 film with integrated prominent performance for potential applications at elevated temperatures.

Brief Theoretical Overview of Bi-Fe-O Based Thin Films

This paper will provide a brief overview of the unique multiferroic material Bismuth ferrite (BFO). Considering that Bismuth ferrite is a unique material which possesses both ferroelectric and magnetic properties at room temperature, the uniqueness of Bismuth ferrite material will be discussed. Fundamental properties of the material including electrical and ferromagnetic properties also will be mentioned in this paper. Electrical properties include characterization of basic parameters considering the electrical resistivity and leakage current. Ferromagnetic properties involve the description of magnetic hysteresis characterization. Bismuth ferrite can be fabricated in a different form. The common forms will be mentioned and include powder, thin films and nanostructures. The most popular method of producing thin films based on BFO materials will be described and compared. Finally, the perspectives and potential applications of the material will be highlighted.

Ultrahigh Ferroelectric and Piezoelectric Properties in BiFeO3-BaTiO3 Epitaxial Films Near Morphotropic Phase Boundary

Ferroelectric solid solutions with composition near the morphotropic phase boundary (MPB) have gained extensive attention recently due to their excellent ferroelectric and piezoelectric properties. Here, we have demonstrated a strategy to realize the controllable preparation of BiFeO₃-BaTiO₃ (BF-BT) epitaxial films near the MPB. A series of high-quality BF-BT films were fabricated by pulsed laser deposition via adjusting oxygen partial pressure (PO₂) using a BF-BT ceramic target. A continuous transition from rhombohedral to tetragonal phase was observed upon increasing PO₂. Particularly, the film with a pure tetragonal phase exhibited a large remnant polarization of ∼90.6 μC/cm², while excellent piezoelectric performance with an ultrahigh strain (∼0.48%) was obtained in the film with coexisting rhombohedral and tetragonal phases. The excellent ferroelectric and piezoelectric properties endow the BF-BT system near the MPB with great application prospects in lead-free electronic devices.