90-degree domain wall relaxation and frequency dependence of the coercive field in the ferr.pdf
文本预览下载声明
190° domain wall relaxation and frequency dependence of the
coercive field in the ferroelectric switching process
M. H. Lente,1 A. Picinin, J. P. Rino, and J. A. Eiras
Universidade Federal de S?o Carlos, Departamento de Física
S?o Carlos, S.P., Brazil, CEP 13560-905
(Received
The mechanisms involved in the polarization switching process in soft and hard Pb(Zr53,
Ti47)O3 (PZT) bulk ceramics were investigated through the dependency of the hysteresis loop on
the frequency. In order to determine the influence of the defects on the domain switching
dynamics the samples were characterized in the virgin state and after a fatigue or a depinning
process. The frequency dependence of the polarization revealed a strong relaxation of the 90°
domain walls at ~100 Hz. The results also revealed a strong influence of the kind of defect and
their distribution into the ferroelectric matrix on the domain switching dynamics, which reflected
in the frequency dependence of the coercive field and the percentage of the backswitching.
Initially, it was observed that the frequency dependence of the coercive field for the soft and the
hard PZT in the virgin state had just one rate of change per decade in all frequency range
investigated, which is the standard behavior found in the literature. However, after the fatigue or
the depinning process two rates of changes were noticed. Consequently, an evidence of an upper
frequency limit for the coercive field changes was found. The percentage of the backswitching
and its behavior for the soft PZT was almost independent of the fatigue state in all frequency
range investigated. Nevertheless, for the hard PZT an opposite behavior was verified. The
reorientation of the domains was modeled as occurring in a viscous medium where several forces
such as viscous and restoring forces act on them.
PACS numbers: 77.80.Fm, 77.80.Dj, 77.22.Ej, 77.22.Jp
1 E-mail: mlente@df.ufscar.br
21. INTRODUCTION
Ferroelectric materials have been widely employed in the technolo
显示全部