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A phase-field model on relaxor ferroelectrics based on random field theory

Wang, Shuai and Xu, Bai-Xiang (2016):
A phase-field model on relaxor ferroelectrics based on random field theory.
In: 2016 Joint IEEE International Symposium on the Applications of Ferroelectrics, European Conference on Applications of Polar Dielectrics & Workshop on Piezoresponse Force Microscopy, Darmstadt, Aug. 21-25, 2016, [Online-Edition: http://www.ieee2016.tu-darmstadt.de/ieee_homepage/inhalt_mit...],
[Conference or Workshop Item]

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Abstract

Relaxor ferroelectrics are a class of disordered crystals with very high piezoelectric effect. In order to reveal its unique physical origins and to explore its application potential, a lot of investigations have been carried out both theoretically and experimentally. In the simulation approach, although there is plenty of work on phase field modeling of conventional ferroelectrics, phase field simulations on relaxor ferroelectrics are scarce in the literature, due to the complex physical origins of relaxor features.

Based on our previous work on ferroelectrics, here we show a phase-field model for relaxor ferroelectrics based on random field theory. Spontaneous polarization is chosen as the order parameter. The random field obeys the Gaussian distribution and its strength can be modified by the variance of the distribution Δ. Finite element simulations based on this model demonstrate that the model can reproduce relaxor features, such as domain miniaturization (Fig. 1), small remnant polarization and large piezoelectric response. Different simulation cases including relaxation process, bipolar loading, pure mechanical loading and electro-mechanical loading shows the capability of the model. Simulation results show that the domain size becomes smaller as the random field becomes stronger in relaxation process, which is in consistent with experimental characterization. Under pure electric loading, the remnant polarization and coercive field becomes smaller as the random field becomes stronger. The remnant polarization decreases with the increase of random fields. When bipolar loading is applied on a preloaded sample, the macroscopic properties such as remnant and maximum polarization can be modified. For instance, the sample with lower random field have smaller remnant polarization, while the sample with higher random field have smaller maximum polarization under compression loading.

Item Type: Conference or Workshop Item
Erschienen: 2016
Creators: Wang, Shuai and Xu, Bai-Xiang
Title: A phase-field model on relaxor ferroelectrics based on random field theory
Language: English
Abstract:

Relaxor ferroelectrics are a class of disordered crystals with very high piezoelectric effect. In order to reveal its unique physical origins and to explore its application potential, a lot of investigations have been carried out both theoretically and experimentally. In the simulation approach, although there is plenty of work on phase field modeling of conventional ferroelectrics, phase field simulations on relaxor ferroelectrics are scarce in the literature, due to the complex physical origins of relaxor features.

Based on our previous work on ferroelectrics, here we show a phase-field model for relaxor ferroelectrics based on random field theory. Spontaneous polarization is chosen as the order parameter. The random field obeys the Gaussian distribution and its strength can be modified by the variance of the distribution Δ. Finite element simulations based on this model demonstrate that the model can reproduce relaxor features, such as domain miniaturization (Fig. 1), small remnant polarization and large piezoelectric response. Different simulation cases including relaxation process, bipolar loading, pure mechanical loading and electro-mechanical loading shows the capability of the model. Simulation results show that the domain size becomes smaller as the random field becomes stronger in relaxation process, which is in consistent with experimental characterization. Under pure electric loading, the remnant polarization and coercive field becomes smaller as the random field becomes stronger. The remnant polarization decreases with the increase of random fields. When bipolar loading is applied on a preloaded sample, the macroscopic properties such as remnant and maximum polarization can be modified. For instance, the sample with lower random field have smaller remnant polarization, while the sample with higher random field have smaller maximum polarization under compression loading.

Uncontrolled Keywords: ferroelectrics, phase field simulation
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
Exzellenzinitiative
Exzellenzinitiative > Graduate Schools
Exzellenzinitiative > Graduate Schools > Graduate School of Computational Engineering (CE)
Event Title: 2016 Joint IEEE International Symposium on the Applications of Ferroelectrics, European Conference on Applications of Polar Dielectrics & Workshop on Piezoresponse Force Microscopy
Event Location: Darmstadt
Event Dates: Aug. 21-25, 2016
Date Deposited: 06 Sep 2016 06:06
Official URL: http://www.ieee2016.tu-darmstadt.de/ieee_homepage/inhalt_mit...
Related URLs:
Funders: The work of Shuai Wang is supported by the 'Excellence Initiative' of the German Federal and State Governments and the Graduate School of Computational Engineering at Technische Universität Darmstadt.
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