Regensburg 2022 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 2: Focus Session: Defects and Interfaces in Multiferroics 1

KFM 2.7: Vortrag

Montag, 5. September 2022, 12:05–12:25, H5

A phase-field model for ferroelectrics with local chemical defects — •Dilshod Durdiev1, Frank Wendler1, Takahiro Tsuzuki2, Shuji Ogata2, Ryo Kobayashi2, Masayuki Uranagase2, and Hikaru Azuma21Friedrich-Alexander University Nuremberg-Erlangen, Fürth, Germany — 2Nagoya Institute of Technology, Nagoya, Japan

In this work, an electromechanical fully coupled phase-field model (PFM) is developed, based upon the approach [1], to study domain evolution and polarization switching under the combined influence of the mechanical and electrical loads and local chemical defects in a BaTiO3 single crystal. The free energy density of the system includes the Landau potential, gradient, mechanical, piezoelectric and electrical energy, respectively. We apply a Fourier spectral method to solve the coupled constitutive equations. Molecular dynamics simulations with core-shell potentials are conducted to capture the domain wall dynamics including vacancies and cation-anion vacancy dipoles [2]. We develop procedures to obtain kinetic and energetic parameters of the PFM from these simulations. Scaling relations are applied to transfer local fields (of vacancies and aliovalent dopants) as well as local bond effects (from vacancies) from the micro- to the continuum scale.

[1] D. Schrade, et al., Arch. Appl. Mech., 83,1393–1413 (2013).

[2] T. Tsuzuki, et al., Appl. Phys. 131, 194101 (2022).

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