Reconciling local structure disorder and the relaxor state in (Bi1/2Na1/2)TiO3 -BaTiO3
|dc.contributor.author||Groszewicz, Pedro B.||ko|
|dc.identifier.citation||SCIENTIFIC REPORTS, v.6, no., pp.31739 -||ko|
|dc.description.abstract||Lead-based relaxor ferroelectrics are key functional materials indispensable for the production of multilayer ceramic capacitors and piezoelectric transducers. Currently there are strong efforts to develop novel environmentally benign lead-free relaxor materials. The structural origins of the relaxor state and the role of composition modifications in these lead-free materials are still not well understood. In the present contribution, the solid-solution (100-x)(Bi1/2Na1/2)TiO3 -xBaTiO3 (BNT-xBT), a prototypic lead-free relaxor is studied by the combination of solid-state nuclear magnetic resonance (NMR) spectroscopy, dielectric measurements and ab-initio density functional theory (DFT). For the first time it is shown that the peculiar composition dependence of the EFG distribution width (��QIS width) correlates strongly to the dispersion in dielectric permittivity, a fingerprint of the relaxor state. Significant disorder is found in the local structure of BNT-xBT, as indicated by the analysis of the electric field gradient (EFG) in 23 Na 3QMAS NMR spectra. Aided by DFT calculations, this disorder is attributed to a continuous unimodal distribution of octahedral tilting. These results contrast strongly to the previously proposed coexistence of two octahedral tilt systems in BNT-xBT. Based on these results, we propose that considerable octahedral tilt disorder may be a general feature of these oxides and essential for their relaxor properties. ? The Author(s) 2016||ko|
|dc.publisher||NATURE PUBLISHING GROUP||ko|
|dc.title||Reconciling local structure disorder and the relaxor state in (Bi1/2Na1/2)TiO3 -BaTiO3||ko|
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