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Diffuse scattering in relaxor ferroelectrics: true three‐dimensional mapping, experimental artefacts and modelling

Diffuse scattering in relaxor ferroelectrics: true three‐dimensional mapping, experimental... The available body of experimental data in terms of the relaxor‐specific component of diffuse scattering is critically analysed and a collection of related models is reviewed; the sources of experimental artefacts and consequent failures of modelling efforts are enumerated. Furthermore, it is shown that the widely used concept of polar nanoregions as individual static entities is incompatible with the experimental diffuse scattering results. Based on the synchrotron diffuse scattering three‐dimensional data set taken for the prototypical ferroelectric relaxor lead magnesium niobate–lead titanate (PMN–PT), a new parameterization of diffuse scattering in relaxors is presented and a simple phenomenological picture is proposed to explain the unusual properties of the relaxor behaviour. The model assumes a specific slowly changing displacement pattern, which is indirectly controlled by the low‐energy acoustic phonons of the system. The model provides a qualitative but rather detailed explanation of temperature, pressure and electric‐field dependence of diffuse neutron and X‐ray scattering, as well as of the existence of a hierarchy in the relaxation times of these materials. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Acta Crystallographica Section A Foundations of Crystallography Wiley

Diffuse scattering in relaxor ferroelectrics: true three‐dimensional mapping, experimental artefacts and modelling

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References (25)

Publisher
Wiley
Copyright
Copyright © 2012 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0108-7673
eISSN
1600-5724
DOI
10.1107/S0108767311040281
pmid
22186288
Publisher site
See Article on Publisher Site

Abstract

The available body of experimental data in terms of the relaxor‐specific component of diffuse scattering is critically analysed and a collection of related models is reviewed; the sources of experimental artefacts and consequent failures of modelling efforts are enumerated. Furthermore, it is shown that the widely used concept of polar nanoregions as individual static entities is incompatible with the experimental diffuse scattering results. Based on the synchrotron diffuse scattering three‐dimensional data set taken for the prototypical ferroelectric relaxor lead magnesium niobate–lead titanate (PMN–PT), a new parameterization of diffuse scattering in relaxors is presented and a simple phenomenological picture is proposed to explain the unusual properties of the relaxor behaviour. The model assumes a specific slowly changing displacement pattern, which is indirectly controlled by the low‐energy acoustic phonons of the system. The model provides a qualitative but rather detailed explanation of temperature, pressure and electric‐field dependence of diffuse neutron and X‐ray scattering, as well as of the existence of a hierarchy in the relaxation times of these materials.

Journal

Acta Crystallographica Section A Foundations of CrystallographyWiley

Published: Jan 1, 2012

Keywords: ; ; ;

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