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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

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

KFM 2.7: Talk

Monday, September 5, 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 Azuma² — ¹Friedrich-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).