Effect of tetragonal distortion on ferroelectric domain switching: A case study on La-doped BiFeO3–PbTiO3 ceramics

The ferroelectric and piezoelectric properties of (1−x)BiFeO3–xPbTiO3 (BF-PT) ceramics were investigated as a function of tetragonal distortion. The latter was adjusted by employing La-doping (0–30 at %) while keeping the material near the morphotropic phase boundary by varying x between 0.35 and 0.46. This allows changing the c/a ratio of tetragonal BF-PT in the range from 1.10–1.01 and consequently alters the level of compatibility stresses. It was found that the c/a ratio has a significant influence on domain switching as inferred from electric field induced polarization, strain hysteresis, and Rayleigh measurements. Specifically, a threshold c/a ratio of about 1.045 was identified below which the electric field induced domain mobility increases sharply.