Impact of Isovalent and Aliovalent Doping on Mechanical Properties of Mixed Phase BiFeO3

Yooun Heo, Songbai Hu, Pankaj Sharma, Kwang Eun Kim, Byung Kweon Jang, Claudio Cazorla, Chan Ho Yang, Jan Seidel

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

In this study, we report the effect of doping in morphotropic BiFeO3 (BFO) thin films on mechanical properties, revealing variations in the elasticity across the competing phases and their boundaries. Spectroscopic force-distance (F-D) curves and force mapping images by AFM are used to characterize the structure and elastic properties of three BFO thin-film candidates (pure-BFO, Ca-doped BFO, La-doped BFO). We show that softening behavior is observed in isovalent La-doped BFO, whereas hardening is seen in aliovalent Ca-doped BFO. Furthermore, quantitative F-D measurements are extended to show threshold strengths for phase transitions, revealing their dependence on doping in the system. First-principles simulation methods are also employed to understand the observed mechanical properties in pure and doped BFO thin films and to provide microscopic insight on them. These results provide key insight into doping as an effective control parameter to tune nanomechanical properties and suggest an alternative framework to control coupled ferroic functionalities at the nanoscale.

Original languageEnglish
Pages (from-to)2805-2813
Number of pages9
JournalACS Nano
Volume11
Issue number3
Early online date24 Feb 2017
DOIs
Publication statusPublished - 28 Mar 2017
Externally publishedYes

Keywords

  • atomic force microscopy
  • density functional theory
  • elastic modulus
  • ferroelectrics
  • morphotropic phase boundary
  • multiferroics
  • nanostructure

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