Polarization switching in (CH3NH3)5Bi2Cl11 ferroelectric crystals

Abstract

The polarization switching in methylammonium chlorobismuthate, (CH 3 NH 3 ) 5 Bi 2 Cl 11 , single crystal was investigated by optical observations of the domain structure and switching current registration. It is shown that defects introduced during crystal growth influence the polarization switching kinetics. For the analysis of switching current data the statistical Avrami model of phase transformation kinetics was employed. Direct observation of the domain structure enabled us to verify the assumptions of the Avrami model in the case of non-uniform (CH 3 NH 3 ) 5 Bi 2 Cl 11 crystals. It is found that application of this model to non-uniform crystals can yield physically unclear values of some fitting parameters; e.g. the effective domain growth dimension is not constant with respect to the electric field.

Stochastic multistep polarization switching in ferroelectrics

“…at the later stages of switching, when approaching the saturated polarization. As compared to the experiment, the analytical calculations exhibit a sharper step-like behavior, typical for the classical KAI-concept [5,7,9] and observed in single crystals [6,7]. In ceramics, however, a more dispersive behavior is typical at longer switching times [7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

“…Previously, macroscopic polarization switching kinetics was described by stochastic models, such as the classical Kolmogorov-Avrami-Ishibashi (KAI) model based on the concept developed to describe melt solidification [2] and assuming random and statistically-independent nucleation and growth of reversed polarized domains in a uniform medium [3,4]. This stochastic model works well for some single crystals [5][6][7] but performs unsatisfactorily when applied to polycrystalline ferroelectric films [8][9][10] or bulk polycrystalline ceramics [11,12]. A range of intrinsic physical features of ferroelectrics are missing in the KAI approach.…”