Enhanced phase transformation in BiFeO3 thin films via synergistic pressure and electric field modulation

In complex multi-field application environments, enhancing the rhombohedral/tetragonal (R/T) phase transition in BiFeO3 (BFO) thin films and making more appearances of R/T morphotropic phase boundaries (MPBs) play a key role in improving the physical properties, such as ferroelectric, piezoelectric, and dielectric, and so on. Therefore, it is particularly important to study the R/T phase transition behavior of the BFO thin films under multi-field conditions. In this paper, the behavior of R/T phase transition in BFO thin films under synergistic modulation of pressure and electric fields is investigated by scanning probe microscopy. Under the condition of pressure-positive voltage synergistic regulation, achieving an R/T MPB with a volume fraction of 35.1% merely requires 3 V, which is lower than the one under a single positive voltage. Under the condition of pressure-negative voltage synergistic regulation, the relationship between the pressure and the voltage is mutual restraint and counterbalance. Under the pressure of above 1.3 μN, the decrease in volume fraction of MPBs is only 1/2 of the one without pressure when the negative voltage is increased from −6 to −10 V. This work provides new ideas and strategies for researching high-performance ferroelectric, piezoelectric, and dielectric devices, holding significant theoretical importance in BFO thin films in complex multi-field application environments.