A novel criterion for nonuniform domain switching of tetragonal ferroelectrics

This paper issues a simple criterion to characterize nonuniform domain switching. The criterion is obtained by minimizing switch-induced system energy change computationally. Combining the numerical result and experimental observations, we propose a quasi-analytic criterion defined by a piecewise function. The piecewise criterion is observed to coincide with the accurate solution very well. As examples, we apply the criterion to: (1) portray a nonhomogeneous switching zone near a stationary crack tip; (2) quantify the switch zone size; (3) predict the volume fractions of ferroelastic and ferroelectric switchings. These predictions all agree with experimental measurements.