FLAME-inars
Our Speakers

24th November 2022 – Talk 25

Advances in Phase-field Simulation of Ferroelectrics and Antiferroelectrics

Prof. Dr. Bai-Xiang Xu Research Group: Mechanics of Functional Materials Institute of Materials Science Technical University of Darmstadt

Abstract

Featured by high power density and high cyclic stability, ferroelectric (FE) and antiferroelectric (AFE) perovskites are distinct type of materials for energy storage and conversion particularly in pulse power equipment, miniaturized electronic devices and electronic control system in electric vehicles. The key issue is to increase the energy storage density, which is strongly related to ferroelectric domain structure in the materials and its interaction with defects.

In this talk, I will present advanced phase-field simulations on the domain scale in such energy materials. In the first part, by combining phase-field simulations with dislocation mechanics and driving force theory (Zhou et al. IJSS 2021 10.1016/j.ijsolstr.2021.111391; Höfling et al. Science, 2021 10.1126/science.abe3810), I will show simulation results and mechanistic understanding on domain wall-dislocation interaction in mechanically hardened ferroelectrics and its impact on properties. In the second part, a high order gradient phase-field model for antiferroelectrics will be presented (Liu and Xu, Script Mat. 2020, 10.1016/j.scriptamat.2020.04.040). It enables simulations of the newly observed incommensurate modulations of (anti-)ferroelectric polarization configuration, which goes beyond the capability of the established models like the Kittel sublattice model. Simulations on the domain structure and hysteresis will be shown, along with the comparison of the simulated temperature induced FE-AFE phase transition with the related experimental results.

Short Biography

  • 04/2016-present: University Professor, Head of the research group Mechanics of Functional Materials, Department of Materials and Geosciences, TU Darmstadt, Germany
  • 08/2011-04/2016: Junior Professor, Head of the research group Mechanics of Functional Materials, Department of Materials and Geosciences, TU Darmstadt, Germany
  • 08/2010-07/2011: Postdoctoral Researcher, Chair of Applied Mechanics, TU Kaiserslautern, Germany
  • 08/2008-07/2010: Alexander von Humboldt Posdoctoral Scholarship, Institute of Solid Mechanics, TU Darmstadt, and Chair of Applied Mechanics, TU Kaiserslautern, Germany
  • 05/2008: Ph.D. (Boshi) in Solid Mechanics, Peking University, China
  • 12/2005-11/2007: Daimler und Benz Scholarship, Institute of Solid Mechanics, TU Darmstadt, Germany
  • 10/2002-07/2008: Graduate Research Assistant at Peking University, China
  • 07/2002: B.Sc. in Solid Mechanics, Hohai University, Nanjing, China

About the FLAME-inars

The FLAME-inars are organized by the collaborative project FLAME at TU Darmstadt, in which electronic-structure-property relationships are being developed and exploited to realize novel lead-free antiferroelectric compounds. The seminars will gather experts in processing, characterization and theory to discuss materials and applications, bulk and thin films, fundamental properties, electronic structure & defects, and related aspects.