Jump to main content
Jump to site search

Issue 35, 2017, Issue in Progress
Previous Article Next Article

Ferroelectric fatigue in layered perovskites from self-energy corrected density functional theory

Author affiliations

Abstract

We employed self-energy corrected density functional theory (GGA-1/2) to investigate the band alignment between platinum and the layered perovskite Aurivillius ferroelectrics SrBi2Ta2O9 (SBT), Bi4Ti3O12 (BIT), and La-substituted BIT (BLT). The original GGA-1/2 method was found to not give satisfactory band gaps for these layered materials, despite yielding substantially better band gaps than GGA. We show that in such layered materials the cutoff radius for the self-energy potential in GGA-1/2 is strongly inhomogeneous across layers, therefore requiring different cutoff radii assigned to oxygen anions located in bismuth oxide layers and in pseudo-perovskite layers. After a 2D optimization of the oxygen cutoff radii, the calculated band gaps for these materials were found within 0.3 eV of experimental values. Next, we developed stoichiometric interface models for Pt/SBT and Pt/BIT, assuming platinum was connected to bismuth oxide layers as suggested by experiments. The calculated Schottky (hole) barriers for abrupt interfaces are 1.58 eV (2.50 eV) and 2.06 eV (1.41 eV) for SBT and BIT, respectively. For Pt(Bi) alloyed interfaces, where according to experiments some Bi diffuses inside the metal, we calculated a downshift of the Fermi level, lowering the barrier for holes. Because the barrier height for holes is lower in Pt/BIT than in Pt/SBT, a higher space-charge-limited-conduction hole current is expected to leak through metal alloyed Pt(Bi)/BIT/Pt(Bi) capacitors than to the corresponding SBT capacitors. Finally, replacing some Bi in the pseudo-perovskite layers with La significantly increased the barrier for holes. Based on the results above, we propose a phenomenological model for ferroelectric fatigue in Pt/BIT/Pt, whereby the formation of a non-ferroelectric Bi-deficient phase is the main reason for fatigue, which is accelerated by the lowered barrier for holes promoting the accumulation of Bi vacancies. The fatigue-free nature of Pt/SBT/Pt and Pt/BLT/Pt, on the other hand, stems from large barriers for both electrons and holes, which prevent the neutralization and further accumulation of charged defects. Our conclusions are consistent with the available experimental data.

Graphical abstract: Ferroelectric fatigue in layered perovskites from self-energy corrected density functional theory

Back to tab navigation

Article information


Submitted
09 Feb 2017
Accepted
03 Apr 2017
First published
19 Apr 2017

This article is Open Access

RSC Adv., 2017,7, 21856-21868
Article type
Paper

Ferroelectric fatigue in layered perovskites from self-energy corrected density functional theory

K. Xue, L. R. C. Fonseca and X. Miao, RSC Adv., 2017, 7, 21856
DOI: 10.1039/C7RA01650F

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material.

Reproduced material should be attributed as follows:

  • For reproduction of material from NJC:
    [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
  • For reproduction of material from PCCP:
    [Original citation] - Published by the PCCP Owner Societies.
  • For reproduction of material from PPS:
    [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
  • For reproduction of material from all other RSC journals:
    [Original citation] - Published by The Royal Society of Chemistry.

Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.


Social activity

Search articles by author

Spotlight

Advertisements