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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 33: Focus Session: (Multi-)Ferroic States V
KFM 33.4: Vortrag
Freitag, 22. März 2024, 10:30–10:50, EMH 225
Parametrization of a ferroelectric phase-field model from MD including nucleation data — •Frank Wendler1, Dilshod Durdiev1, Michael Zaiser1, Takahiro Tsuzuki2, Hikaru Azuma2, Shuji Ogata2, Ryo Kobayashi2, and Masayuki Uranagase2 — 1Institute of Materials Simulation, Friedrich-Alexander-Universität Erlangen-Nürnberg, Dr.-Mack-Str. 77, 90762 Fürth, Germany. — 2Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-9555, Japan
Phase-field models based on the Landau-Ginzburg-Devonshire theory extend the time and length scales in comparison to molecular dynamics (MD) simulations, and enable a bottom-up approach to generate a complete energy landscape purely from atomistic information.Crucial material parameters such as elastic and piezoelectric properties, kinetic coefficients, as well as domain wall characteristics are extracted from MD data to adjust anisotropic gradient energy. To bridge the gap between the atomistic and continuum model, a proposed parametrization workflow involves determining all coefficients for the 6th order Landau polynomial from polarization reversal characteristics. Polarization switching in ferroelectric barium titanate (BTO) involves localized nucleation and subsequent domain growth, driven by an applied electric field. MD simulation data proves the role of thermal activation in domain nucleation, resulting in a notable scatter in coercive fields within small systems. From this data we calculate the activation parameters for BTO that govern polarization switching at coercive fields not only for perfect, but also those containing vacancy defects.
Keywords: phase-field; molecular dynamics; parametrization; ferroelectric hysteresis; thermal activation