Analysis of ferroelectric polarization switching in (NH4)0.39K0.61NO3 films using nucleation limited switching model

Abstract

The polarization switching transients of spray deposited ferroelectric (NH4)0.39K0.61NO3 (NKN) films has been analyzed with nucleation limited switching (NLS) model by considering domain growth limited process. The experimentally measured microscopic polarization switching curves fitted well with NLS model and the characteristic switching times obeyed the Lorentzian distribution function. The local field variation was found to be minimum at pulse amplitude 15 V, which makes the polarization reversal more probable. The value of spontaneous polarization, Ps and coercive field, Ec was found to be 6.58 μC/cm2 and 4.10 kV/cm, respectively. The value of Ps from the switching and P-E loop is in good agreement with each other. The field emission scanning electron microscopy and atomic force microscopy images of the NKN film reveal the formation of nanoparticles of NKN.

Statistical electric field and switching time distributions in PZT 1Nb2Sr ceramics: Crystal- and microstructure effects

“…23 Further development of the IR approach resulted in a concept, named the inhomogeneous field mechanism (IFM) model, 15,18 which leaves the form of the statistical field distribution a priori unspecified, while at the same time it provides a calculation scheme which allows for the computation of this distribution from the experimental data. In contrast to the other IR models, 12,16,17,19 the IFM model tries to relate the non-uniform switching behaviour to the random spatial distribution of the applied electric field. This procedure provides a chance to identify patterns in the field distributions that are typical for specific structural and microstructural features or the materials state and to correlate the shape and parameters of the field distribution with the materials characteristics.…”

“…Additionally, this analysis allows for the investigation of the microscopic characteristics of the local polarization switching, such as the dependence of the local switching time sðEÞ on the value of the local electric field E. The other details of the microscopic switching process are neglected in the IMF model by assuming that switching of a local region occurs instantly as soon as the poling time exceeds respective sðEÞ. An essential limitation of the IMF concept 15,18 and of the other IR models 12,16,17,19 is that the spatial random field distribution is assumed to be static thus neglecting contribution of the time-dependent depolarization fields which develop in the course of polarization switching. Recent self-consistent simulations of polarization switching in bulk polycrystalline ferroelectrics show, however, that account of field-mediated polarization correlations leads to a strong reduction of the local depolarization fields thus supporting the static IMF concept.…”

“…[3][4][5][6][7][8][9][10] Nucleation and growth of reversed domains are alternatively considered to both require time to become effective for domain switching and related polarization reversal. The second concept favours models, comprising the statistical approach, [11][12][13][14][15][16][17][18][19][20] which are based on the assumption that conditions for switching given by the local environment are different in different areas of the ceramics, which leads to a distribution of switching times. The feature common to these models can be summarized by the intrinsic randomness (IR) of the local conditions for switching.…”

“…Accordingly, the Lorentzian distribution of local random fields was used to describe the polarization reversal in thin ferroelectric films. 12,16,17 Alternatively, a Gaussian distribution of local random fields was applied to describe the dispersive a)…”

Polarization dynamics across the morphotropic phase boundary in Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 ferroelectrics

“…3 To obtain microscopic parameters providing the macroscopic switching process, more sophisticated theories are required, which account for a statistical distribution of local switching times in a system. [4][5][6][7][8] To this end, the inhomogeneous field mechanism (IFM) model is used in this paper, which derives the distribution of times from the distribution of randomly distributed local field values. 7,8 The lead-free (1Àx)Ba(Zr 0.2 Ti 0.8 )O 3 -x(Ba 0.7 Ca 0.3 )TiO 3 ferroelectrics (referred to as BCZT100x hereafter) were chosen for this case study for their prominent properties, which are discussed in the following.…”