Origin of Grain Size Effects on Voltage‐Driven Ferroelastic Domain Evolution in Polycrystalline Tetragonal Lead Zirconate Titanate Thin Film

Grain size effects on electromechanical properties and voltage‐driven ferroelastic domain wall motion are a well‐known phenomenon in polycrystalline ferroelectrics. Here, the origin of the grain size effects on voltage‐driven ferroelastic domain wall motion is presented with the direct observation of ferroelastic domain evolution with applied DC voltage by piezoelectric force microscopy and polarization hysteresis loop. It is demonstrated that the microstructure parameter for controlling the voltage‐driven ferroelastic domain wall motion is the number of colonies of stripe domains in a grain rather than the grain size. Single colony grains do not show considerable out‐of‐plane (001) domain width change whereas multiple colony grains exhibit significant domain width increase with an applied DC voltage. No independent grain size effect on ferroelastic domain wall motion is observed in the grain size range 0.6–1.6 µm.