Exposing and Controlling the Atomic-scale Behavior in BaTiO3 with In-situ Electron Microscopy

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Mrs. Maya Barzilay, PhD. Candidate

21.06.2020

סמינר ב-ZOOM

14:30

Ferroelectric are functional perovskites that demonstrate reversible spontaneous polarization. The polarization arises due to synchronized distortion of the unit cells that give rise to collective organization of atomic-scale dipole moments in the form of domains. Although the macroscale behavior of ferroelectricity is well known, the microscale origin has remained elusive, mainly due to the lack of suitable tools to explore systems with collective electron and ion interactions. Here, we combined advanced structural, chemical and electric characterization, using electron microscopy with in-situ excitations to demonstrate the origin of domain formation and stabilization in the seminal ferroelectric, BaTiO3. We show that the ferroelectric-to-paraelectric transition emerges by formation of two-unit-cell nuclei near the surface that expand by sidewalk toward the bulk. We also demonstrate that the ferroelectric surface consists of a non-stoichiometric TiOx phase, which is proposed to stabilize the bulk polarization electro-chemo-mechanically. Similarly, we show that domains are stabilized due to organized oxygen vacancies. Finally, by applying in-situ contactless electric field, nucleation, growth and switching of domains as small as 2 nm was illustrated, as well as an irregular sushi-rolling-like piezoresponse.

References:

  1. M. Barzilay at el. ACS Appl Elec Mat. 2019, 1, 11, 2431-2436.
  2. M. Barzilay, at el. Adv Func Mat. 2019, 1902549
  3. M. Barzilay, at el. Nanoscale. 2020, DOI: 10.1039/D0NR01747G.
  4. H. Elangovan, M. Barzilay at el. ACS Nano. 2020. 14, 4, 5053-506

Advisor: Asst Prof. Yachin Ivry

Seminar by Zoom: Click here