Refining perovskite structures to pair distribution function data using collective Glazer modes as a basis

Sandra Helen Skjærvø, Martin A. Karlsen, Riccardo Comin, Simon J.L. Billinge*

*Kontaktforfatter

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

28 Downloads (Pure)

Abstract

Structural modelling of octahedral tilts in perovskites is typically carried out using the symmetry constraints of the resulting space group. In most cases, this introduces more degrees of freedom than those strictly necessary to describe only the octahedral tilts. It can therefore be a challenge to disentangle the octahedral tilts from other structural distortions such as cation displacements and octahedral distortions. This paper reports the development of constraints for modelling pure octahedral tilts and implementation of the constraints in diffpy-CMI, a powerful package to analyse pair distribution function (PDF) data. The model in the program allows features in the PDF that come from rigid tilts to be separated from non-rigid relaxations, providing an intuitive picture of the tilting. The model has many fewer refinable variables than the unconstrained space group fits and provides robust and stable refinements of the tilt components. It further demonstrates the use of the model on the canonical tilted perovskite CaTiO3 which has the known Glazer tilt system α+β-β-. The Glazer model fits comparably to the corresponding space-group model Pnma below r = 14 Å and becomes progressively worse than the space-group model at higher r due to non-rigid distortions in the real material.

OriginalsprogEngelsk
TidsskriftIUCrJ
Vol/bind9
Udgave nummer5
Sider (fra-til)705-712
Antal sider8
ISSN2052-2525
DOI
StatusUdgivet - 1. sep. 2022

Bibliografisk note

Publisher Copyright:
© 2022 International Union of Crystallography. All rights reserved.

Fingeraftryk

Dyk ned i forskningsemnerne om 'Refining perovskite structures to pair distribution function data using collective Glazer modes as a basis'. Sammen danner de et unikt fingeraftryk.

Citationsformater