Zhi Wang¹, Jinming Cao¹, Zhonglei Liu¹, Yuhong Zhao^1,2,3,*

CMC-Computers, Materials & Continua, Vol.81, No.1, pp. 213-228, 2024, DOI:10.32604/cmc.2024.055169 - 15 October 2024

Abstract Recent years, the polarization response of ferroelectrics has been entirely studied. However, it is found that the polarization may disappear gradually with the continually applied of electric field. In this paper, taking K_0.48Na_0.52NbO₃(KNN) as an example, it was demonstrated that the residual polarization began to decrease when the electric field frequency increased to a certain extent using a phase-field methods. The results showed that the content of out-of-plane domains increased first and then decreased with the increase of applied electric field frequency, the maximum polarization disappeared at high frequencies, and the hysteresis loop became elliptical. In More >

Xiaoyan Lu^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.29, No.3, pp. 1-1, 2024, DOI:10.32604/icces.2024.012507

Abstract Ferroelectric materials usually experience various phase under external temperature, electric and stress fields. Unique properties such as piezoelectricity, dielectricity, polarization reversal, and phase transitions are widely used in various electronic devices. Particularly, the phase and domain structures, ferroelastic switching behaviors often play a crucial role in determining their dielectric and piezoelectric properties. Here, we report some abnormal behaviors in ferroelectric thin films and single crystals, from which, we build the Landau theoretical model for relaxor ferroelectric single crystals. Using this model, we studied the phase coexistence and the corresponding physical properties. Using the results, we More >

Yong Zhang^1,*, Jie Wang^2,3

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.1, pp. 1-1, 2023, DOI:10.32604/icces.2023.09368

Abstract Ferroelectric materials have been widely used in various electromechanical devices such as sensors, actuators, transducers and energy storage devices due to their distinguished electromechanical coupling properties. Ferroelectric materials usually bear large mechanical loads and high electric fields in order to give full play to their potential. The interaction between fracture and dielectric breakdown is able to occur since the filler inside a crack will change the dielectric behaviors around it and dielectric breakdown can change the local mechanical properties of dielectric materials because of its weakening of chemical bonds. Therefore, a comprehensive and in-depth understanding… More >

Peter L. Bishay¹, Satya N. Atluri¹

CMC-Computers, Materials & Continua, Vol.33, No.1, pp. 19-62, 2013, DOI:10.3970/cmc.2013.033.019

Abstract In this paper, 2D and 3D Multiphysics Voronoi Cells (MVCs) are developed, for the Direct Mesoscale Numerical Simulation (DMNS) of the switching phenomena in ferroelectric polycrystalline materials. These arbitrarily shaped MVCs (arbitrary polygons in 2D, and arbitrary polyhedrons in 3D with each face being an arbitrary polygon) are developed, based on assuming radial basis functions to represent the internal primal variables (mechanical displacements and electric potential), and assuming linear functions to represent the primal variables on the element boundaries. For the 3D case, the linear functions used to represent the primal variables on each of… More >

Yifan Xia, Jie Wang

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.3, pp. 87-88, 2011, DOI:10.3970/icces.2011.020.087

Abstract Phase field simulation is an effective way to predict the domain evolution in ferroelectric materials. A phase field model is developed to investigate the domain structures and polarization switching in in ferroelectric thin films with deadlayers. Simulation results show that the deadlayers as well as misfit strain have a significant influence on the domain structures and polarization switching in the ferroelectric thin films. It is found that the simulated switching electric field in ferroelectric thin films decreases with the thickness of the deadlayers increasing. More >

Jie Wang

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.3, pp. 77-78, 2011, DOI:10.3970/icces.2011.020.077

Abstract Ferroelectric nanostructures exhibit vortex structures with the shrinking of the relevant lengths to the nanometer scale because of the strong depolarization field. The vortex structure in the nanoscale ferroelectrics, similar to the vortex structure in magnetic nanostructure, is regarded as a toroidal order which is different from the common homogeneous polarization order. The finding of the vortex in ferroelectric nanostructures opens exciting opportunities for designing nanomemory devices, which holds a promise to increase the density of ferroelectric nonvolatile random access memories by several orders of magnitude. The switching behavior of polarization vortex under a curled… More >

K. Jayabal, A. Arockiarajan, S.M. Sivakumar¹

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.1&2, pp. 111-124, 2008, DOI:10.3970/cmes.2008.027.111

Abstract A three dimensional micromechanically motivated model is proposed here based on firm thermodynamics principles to capture the nonlinear dissipative effects in the polycrystal ferroelectrics. The constraint imposed by the surrounding grains on a subgrain at its boundary during domain switching is modeled by a suitable modification of the switching threshold in a subgrain. The effect of this modification in the dissipation threshold is studied in the polycrystal behavior after due correlation of the subgrain behavior with the single crystal experimental results found in literature. Taking into consideration, all the domain switching possibilities, the volume fractions More >

Mustafa Uludoğan¹, D. Paula Guarin¹, Zully E. Gomez¹, Tahir Cagin¹, William A. Goddard III²

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 215-238, 2008, DOI:10.3970/cmes.2008.024.215

Abstract Aiming at a presentation of the utility of the state of art of first-principles methods (PBE flavor of Density Functional Theory, DFT) in the area of materials science and engineering, we present our studies of the equation of state and ferroelectric-paraelectricphase transition in several ferroelectric systems, including BaTiO₃, PbTiO₃, SrTiO₃, AgNbO₃, Pb_xBa_1-xTiO₃ and Sr_xBa_1-xTiO₃. We also report the Born effective charges, optical dielectric constant, and phonon dispersion relation properties from Density Functional Perturbation Theory. Computed results are compared with other theoretical results (which were mostly on BaTiO₃, PbTiO₃, cubic SrTiO₃ using various approaches, as well as experiments. The studies on More >

Jie Wang¹, Tong-Yi Zhang¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.1, pp. 1-8, 2007, DOI:10.3970/icces.2007.003.001

Abstract Two-dimensional phase field simulations of stress-free ferroelectric nanoparticles with different long-range (LR) electrostatic interactions are conducted based on the time-dependent Ginzburg-Landau equation. Polarization patterns and the toroidal moment of polarization are found to be dependent on the LR electrostatic interaction and the size of the simulated nanoparticle. Phase field simulations exhibit vortex patterns with purely toroidal moments of polarization and negligible macroscopic polarization in the stress-free ferroelectric nanoparticles when the LR electrostatic interaction is fully taken into account. However, a single-domain structure without any toroidal moment of polarization is formed in small particles if the More >