Structural and magnetic characterisation of Aurivillius material Bi{sub 2}Sr{sub 2}Nb{sub 2.5}Fe{sub 0.5}O{sub 12}
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)
The n=3 Aurivillius material Bi{sub 2}Sr{sub 2}Nb{sub 2.5}Fe{sub 0.5}O{sub 12} is investigated and combined structural refinements using neutron powder diffraction (NPD) and X-ray powder diffraction data (XRPD) data reveal that the material adopts a disordered, tetragonal (I4/mmm) structure at temperatures down to 2 K. Significant ordering of Fe{sup 3+} and Nb{sup 5+} over the two B sites is observed and possible driving forces for this ordering are discussed. Some disorder of Sr{sup 2+} and Bi{sup 3+} over the M and A sites is found and is consistent with relieving strain due to size mismatch. Highly anisotropic thermal parameters for some oxygen sites suggest that the local structure may be slightly distorted with some rotation of the octahedra. Magnetic measurements show that the material behaves as a Curie-Weiss paramagnet in the temperature range studied with no evidence of any long-range magnetic interactions. Solid solutions including Bi{sub 3-x}Sr{sub x}Nb{sub 2}FeO{sub 12}, Bi{sub 2}Sr{sub 2-x}La{sub x}Nb{sub 2}FeO{sub 12} and Bi{sub 2}Sr{sub 2}Nb{sub 3-x}Fe{sub x}O{sub 12} were investigated but single-phase materials were only successfully synthesised for a narrow composition range in the Bi{sub 2}Sr{sub 2}Nb{sub 3-x}Fe{sub x}O{sub 12} system. - Graphical abstract: We report here the synthesis and characterisation of the Aurivillius material Bi{sub 2}Sr{sub 2}Nb{sub 2.5}Fe{sub 0.5}O{sub 12}. Combined Rietveld refinements using NPD and XRPD data have been used to investigate the structure and suggest that the material shows significant cation ordering as well as some local structural distortions. Bi{sub 2}Sr{sub 2}Nb{sub 2.5}Fe{sub 0.5}O{sub 12} is paramagnetic in the temperature range studied.
- OSTI ID:
- 21212102
- Journal Information:
- Journal of Solid State Chemistry, Vol. 181, Issue 11; Other Information: DOI: 10.1016/j.jssc.2008.08.004; PII: S0022-4596(08)00425-8; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANISOTROPY
BISMUTH COMPOUNDS
BISMUTH IONS
CATIONS
INTERACTIONS
IRON IONS
NEUTRON DIFFRACTION
NIOBIUM COMPOUNDS
NIOBIUM IONS
OXYGEN COMPOUNDS
PARAMAGNETISM
ROTATION
SOLID SOLUTIONS
STRAINS
STRONTIUM COMPOUNDS
STRONTIUM IONS
SYNTHESIS
TETRAGONAL LATTICES
X-RAY DIFFRACTION