Stochastic multistep polarization switching in ferroelectrics

Abstract

Consecutive stochastic 90° polarization switching events, clearly resolved in recent experiments, are described by a new nucleation and growth multi-step model. It extends the classical Kolmogorov-Avrami-Ishibashi approach and includes possible consecutive 90°-and parallel 180°-switching events. The model predicts the results of simultaneous time-resolved macroscopic measurements of polarization and strain, performed on a tetragonal Pb(Zr,Ti)O3 ceramic in a wide range of electric fields over a time domain of five orders of the magnitude. It allows the determination of the fractions of individual switching processes, their characteristic switching times, activation fields, and respective Avrami indices.

Stochastic model of dispersive multi-step polarization switching in ferroelectrics due to spatial electric field distribution

“…A = 32.5 kV/mm. Macroscopic parameters are in reasonable agreement with independently measured polarization and strain characteristics 23 . The determination of the microscopic fitting parameters has an inaccuracy below 1.3% for α, β, γ, κ and η, and below 0.5% for activation fields E (i) A .…”

“…The formulas (4-7), from now on termed as the MSM-NLS approach, were used to fit simultaneous temporal measurements of polarization and strain response of Pb 0.985 La 0.01 (Zr 0.475 Ti 0.525 )O 3 ceramic with tetragonal phase symmetry 23 . We note that the only additional fitting parameter in comparison with Eqs.…”

“…The fair quality of the fitting may result from the relatively narrow field distribution function, Eq. (5), which limits the validity of the used step-function approximation23 . It is expected that the performance of the MSM-IFM approach will be better for systems with broader field distributions.Introduction of the statistical distribution of local field values remarkably improved the description of the electromechanical response, as compared with the MSM model 23 assuming the uniform electric field.…”

Influence of crystallographic structure on polarization reversal in polycrystalline ferroelectric/ferroelastic materials

“…Field-dependent measurements were also used to determine the activation fields for each event, which are important parameters for micromechanical models. 19 Moreover, these measurements can be used as input for the recently developed multistep stochastic mechanism model, 77 which allows quantifying the contribution of 180°and non-180°s witching events.…”

Polarization Reversal Via a Transient Relaxor State in Nonergodic Relaxors Near Freezing Temperature

“…This means that the thermal energy required for depolarizing the electrically textured state is smaller than that for disrupting electrically-induced longrange ferroelectric order. As aforementioned, these stepwise processes are absent in normal ferroelectrics [27,28]. Given this, the polarization reversal near T d should, in fact, occur in three steps: 1) poled state decays into randomly oriented domains, 2) detexturized ferroelectric state breaks down to macroscopic relaxor state, 3) textured ferroelectric state aligned in the opposite direction is manifested [29].…”