Complex Structural Disorder in a Polar Orthorhombic Perovskite Observed through the Maximum Entropy Method/Rietveld Technique

Alicia María Manjón-Sanz, T. Wesley Surta, Pranab Mandal, Alex J. Corkett, Hongjun Niu, Eiji Nishibori, Masaki Takata, John Bleddyn Claridge, Matthew J. Rosseinsky

Research output: Contribution to journalArticlepeer-review

Abstract

Ambient pressure stable perovskite oxides with all Bi3+ on the A-site are rare, with only four examples known. Due to the lone pair on Bi3+, these materials are seen as the best alternative to Pb-based piezoelectrics, which are used widely in society. The industry standard piezoelectric, Pb (Zr1 - xTix)O3, relies on the [001] polarization of PbTiO3, but there are currently no ambient pressure stable Bi-based perovskites with this polarization vector, preventing the creation of an analogous system. We present the full structural analysis of the orthorhombic phase of (1 - x)Bi (Ti3/8Fe2/8Mg3/8)O3 - xCaTiO3, which crystallizes in Pna21 symmetry with [001] polarization. This symmetry is rare and has only been reported twice for perovskites at ambient conditions. Analysis of maximum entropy method (MEM) models using synchrotron radiation powder X-ray diffraction reveals a disordered A-site configuration, and the MEM/Rietveld technique generates a structural model of this extreme disorder. Combined Rietveld analysis of X-ray and neutron diffraction data yields an accurate description of the local A-site configuration, which we use to understand our dielectric, ferroelectric, and piezoelectric measurements. These results give insight into how to stabilize this unique symmetry and inspire new design principles for Bi-based piezoelectrics.

Original languageEnglish
Pages (from-to)29-42
Number of pages14
JournalChemistry of Materials
Volume34
Issue number1
DOIs
Publication statusPublished - 2022 Jan 11

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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