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Local deformation gradients in epitaxial Pb(Zr0.2Ti0.8)O-3 layers investigated by transmission electron microscopy

Denneulin, T., Wollschlaeger, N., Everhardt, A. S., Farokhipoor, S., Noheda, B., Snoeck, E. & Hytch, M., 31-May-2018, In : Journal of Physics-Condensed Matter. 30, 21, 11 p., 215701.

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  • Local deformation gradients in epitaxial Pb(Zr 0.2 Ti 0.8 )O 3 layers investigated by transmission electron microscopy

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DOI

  • T. Denneulin
  • N. Wollschlaeger
  • A. S. Everhardt
  • S. Farokhipoor
  • B. Noheda
  • E. Snoeck
  • M. Hytch

Lead zirconate titanate samples are used for their piezoelectric and ferroelectric properties in various types of micro-devices. Epitaxial layers of tetragonal perovskites have a tendency to relax by forming 90 degrees ferroelastic domains. The accommodation of the a/c/a/c polydomain structure on a flat substrate leads to nanoscale deformation gradients which locally influence the polarization by flexoelectric effect. Here, we investigated the deformation fields in epitaxial layers of Pb(Zr0.2Ti0.8)O-3 grown on SrTiO3 substrates using transmission electron microscopy (TEM). We found that the deformation gradients depend on the domain walls inclination (+45 degrees or -45 degrees to the substrate interface) of the successive 90 degrees domains and we describe three different a/c/a domain configurations: one configuration with parallel a-domains and two configurations with perpendicular a-domains (V-shaped and hat-Lambda-shaped). In the parallel configuration, the c-domains contain horizontal and vertical gradients of out-of-plane deformation. In the V-shaped and hat-Lambda-shaped configurations, the c-domains exhibit a bending deformation field with vertical gradients of in-plane deformation. Each of these configurations is expected to have a different influence on the polarization and so the local properties of the film. The deformation gradients were measured using dark-field electron holography, a TEM technique, which offers a good sensitivity (0.1%) and a large field-of-view (hundreds of nanometers). The measurements are compared with finite element simulations.

Original languageEnglish
Article number215701
Number of pages11
JournalJournal of Physics-Condensed Matter
Volume30
Issue number21
Publication statusPublished - 31-May-2018

    Keywords

  • ferroelectric, PZT, strain, electron holography, TEM, FERROELASTIC DOMAIN-WALLS, FERROELECTRIC THIN-FILMS, MISFIT DISLOCATIONS, STRAIN RELAXATION, 1ST PRINCIPLES, PBTIO3 FILMS, POLARIZATION, HETEROSTRUCTURES, INTERFEROMETRY, PEROVSKITES

ID: 60241445