The relation of local order to material properties in relaxor ferroelectrics

Correlating electromechanical and dielectric properties with nanometre-scale order is the defining challenge for the development of piezoelectric oxides. Current lead (Pb)-based relaxor ferroelectrics can serve as model systems with which to unravel these correlations, but the nature of the local or...

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Bibliographic Details
Published in:Nature materials 2018-08, Vol.17 (8), p.718-724
Main Authors: Krogstad, M. J., Gehring, P. M., Rosenkranz, S., Osborn, R., Ye, F., Liu, Y., Ruff, J. P. C., Chen, W., Wozniak, J. M., Luo, H., Chmaissem, O., Ye, Z.-G., Phelan, D.
Format: Article
Language:English
Subjects:
639/301/119/996
639/766/119/1002
Antiferroelectricity
Biomaterials
Chemistry and Materials Science
Condensed Matter Physics
Correlation
Crystals
Dependence
Dielectric properties
Dielectric relaxation
Electrical properties
Ferroelectric materials
Ferroelectrics
Instrumentation
Lead
Material properties
MATERIALS SCIENCE
Nanotechnology
Optical and Electronic Materials
Organic chemistry
Piezoelectricity
Relaxors
Scattering
Short range order
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Summary:Correlating electromechanical and dielectric properties with nanometre-scale order is the defining challenge for the development of piezoelectric oxides. Current lead (Pb)-based relaxor ferroelectrics can serve as model systems with which to unravel these correlations, but the nature of the local order and its relation to material properties remains controversial. Here we employ recent advances in diffuse scattering instrumentation to investigate crystals that span the phase diagram of PbMg 1/3 Nb 2/3 O 3 - x PbTiO 3 (PMN- x PT) and identify four forms of local order. From the compositional dependence, we resolve the coupling of each form to the dielectric and electromechanical properties observed. We show that relaxor behaviour does not correlate simply with ferroic diffuse scattering; instead, it results from a competition between local antiferroelectric correlations, seeded by chemical short-range order, and local ferroic order. The ferroic diffuse scattering is strongest where piezoelectricity is maximal and displays previously unrecognized modulations caused by anion displacements. Our observations provide new guidelines for evaluating displacive models and hence the piezoelectric properties of environmentally friendly next-generation materials. How local order affects the excellent piezoelectric properties of Pb-based relaxor ferroelectrics is unclear, but neutron diffuse scattering shows that non-relaxor distortions are implicated, indicating the important role of oxygen atoms.
ISSN:1476-1122
1476-4660
DOI:10.1038/s41563-018-0112-7