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Title: Designing new n=2 Sillen–Aurivillius phases by lattice-matched substitutions in the halide and [Bi{sub 2}O{sub 2}]{sup 2+} layers

A new n=2 Sillen–Aurivillius compound Bi{sub 3}Sr{sub 2}Nb{sub 2}O{sub 11}Br has been synthesised based on Bi{sub 3}Pb{sub 2}Nb{sub 2}O{sub 11}Cl by simultaneously replacing Pb{sup 2+} with Sr{sup 2+} and Cl{sup −} with Br{sup −}. Rietveld refinements against X-ray and neutron powder diffraction data revealed a significant relative compression in the stacking axis (c-axis) of the new compound. Sr{sup 2+} doping reduces the impact of the stereochemically active 6s{sup 2} lone pair found on Pb{sup 2+} and Bi{sup 3+}, resulting in a contraction of the c-axis by 1.22% and an expansion of the ab plane by 0.25%. This improves the inter-layer compatibility with the larger halide Br{sup −}. Analysis of X-ray absorption near-edge spectroscopy data show that the ferroelectric distortion of the B-site cation is less apparent in Bi{sub 3}Sr{sub 2}Nb{sub 2}O{sub 11}Br compared to Bi{sub 3}Pb{sub 2}Nb{sub 2}O{sub 11}Cl, and variable-temperature neutron diffraction data show no evidence for a ferroelectric distortion. - Graphical abstract: The structural expansion and contractions in the stacking axis of co-doped Sillen–Aurivillius phases. Display Omitted - Highlights: • A new Sillen–Aurivillius phase Bi{sub 3}Sr{sub 2}Nb{sub 2}O{sub 11}Br is synthesised based on Bi{sub 3}Pb{sub 2}Nb{sub 2}O{sub 11}Cl. • The stacking axis contracts although local expansion accommodates themore » larger halide Br. • Majority of the contraction is observed in the [Bi{sub 2}O{sub 2}]{sup 2+} layers where we replaced Pb{sup 2+} for Sr{sup 2+}. • Removing the Pb{sup 2+} lowers the lone pair effect and improves inter-layer compatibility. • XANES and NPD suggest that the ferroelectric properties are minimised or suppressed.« less
Authors:
 [1] ;  [1] ;  [2] ; ;  [1]
  1. School of Chemistry, University of Sydney, Sydney 2006 (Australia)
  2. The Bragg Institute, ANSTO, PMB 1, Menai 2234 (Australia)
Publication Date:
OSTI Identifier:
22274086
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 205; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; ABSORPTION; ABSORPTION SPECTROSCOPY; BISMUTH IONS; CATIONS; COMPRESSION; CONTRACTION; DESIGN; DOPED MATERIALS; EXPANSION; FERROELECTRIC MATERIALS; HALIDES; LAYERS; LEAD IONS; NEUTRON DIFFRACTION; NEUTRON TEMPERATURE; OXYBROMIDES; STRONTIUM IONS; SYNTHESIS; X RADIATION; X-RAY SPECTROSCOPY