Structural variations in pyrochlore-structured Bi2Hf2O7, Bi2Ti2O7 and Bi2Hf2-xTixO7 solid solutions as a function of composition and temperature by neutron and X-ray diffraction and Raman spectroscopy
Structural variations in pyrochlore-structured Bi2Hf2O7, Bi2Ti2O7 and Bi2Hf2-xTixO7 solid solutions as a function of composition and temperature by neutron and X-ray diffraction and Raman spectroscopy
The structural behavior of the pyrochlore Bi2Hf2O7 with varying temperature has been studied by powder neutron diffraction X-ray diffraction, and Raman scattering. The unit cell undergoes phase changes that are determined by diffraction methods to occur between -, -, - and -polymorphs at around 400, 550 and 900 C. The -Bi2Hf2O7 polymorph corresponds to the ideal cubic pyrochlore phase. Three of the four polymorphs have previously been reported to occur for Bi2Sn2O7. The need to accommodate the active Bi3+ lone pair in the presence of large HfO6 octahedra results in an "icelike" ordering of Bi positions in Bi2Hf2O7 at room temperature. A similar sequence of phase transitions is observed at room temperature with increasing Ti4+ for Hf4+ substitution in the compositional series Bi2Hf2-xTixO7. The structure changes as the space available to the Bi3+ ion increases represent a gradual increase in disorder and symmetry.
phases, phonon, dielectric-properties, spectrum, dynamics, soft, bi2sn2o7, dependence, srtio3, strontium titanate, crystal-chemistry
1712-1722
Henderson, S.J.
1c3f4b44-e1e9-4857-ac65-4243c0ed3835
Shebanova, O.
80c3b7a9-dd6d-40ff-9392-6442fe405e91
Hector, A.L.
f19a8f31-b37f-4474-b32a-b7cf05b9f0e5
McMillan, P.F.
d1f457d0-a41f-451f-b2e4-15458fd47fec
Weller, M.T.
36a60b56-049f-466c-a1d7-39d6b0d85ff4
2007
Henderson, S.J.
1c3f4b44-e1e9-4857-ac65-4243c0ed3835
Shebanova, O.
80c3b7a9-dd6d-40ff-9392-6442fe405e91
Hector, A.L.
f19a8f31-b37f-4474-b32a-b7cf05b9f0e5
McMillan, P.F.
d1f457d0-a41f-451f-b2e4-15458fd47fec
Weller, M.T.
36a60b56-049f-466c-a1d7-39d6b0d85ff4
Henderson, S.J., Shebanova, O., Hector, A.L., McMillan, P.F. and Weller, M.T.
(2007)
Structural variations in pyrochlore-structured Bi2Hf2O7, Bi2Ti2O7 and Bi2Hf2-xTixO7 solid solutions as a function of composition and temperature by neutron and X-ray diffraction and Raman spectroscopy.
Chemistry of Materials, 19 (7), .
(doi:10.1021/cm062864a).
Abstract
The structural behavior of the pyrochlore Bi2Hf2O7 with varying temperature has been studied by powder neutron diffraction X-ray diffraction, and Raman scattering. The unit cell undergoes phase changes that are determined by diffraction methods to occur between -, -, - and -polymorphs at around 400, 550 and 900 C. The -Bi2Hf2O7 polymorph corresponds to the ideal cubic pyrochlore phase. Three of the four polymorphs have previously been reported to occur for Bi2Sn2O7. The need to accommodate the active Bi3+ lone pair in the presence of large HfO6 octahedra results in an "icelike" ordering of Bi positions in Bi2Hf2O7 at room temperature. A similar sequence of phase transitions is observed at room temperature with increasing Ti4+ for Hf4+ substitution in the compositional series Bi2Hf2-xTixO7. The structure changes as the space available to the Bi3+ ion increases represent a gradual increase in disorder and symmetry.
This record has no associated files available for download.
More information
Submitted date: 3 December 2006
Published date: 2007
Keywords:
phases, phonon, dielectric-properties, spectrum, dynamics, soft, bi2sn2o7, dependence, srtio3, strontium titanate, crystal-chemistry
Organisations:
Chemistry
Identifiers
Local EPrints ID: 44838
URI: http://eprints.soton.ac.uk/id/eprint/44838
ISSN: 0897-4756
PURE UUID: a6fdc8ae-5a53-4dbd-ac29-46a13960c81c
Catalogue record
Date deposited: 16 Mar 2007
Last modified: 16 Mar 2024 02:53
Export record
Altmetrics
Contributors
Author:
S.J. Henderson
Author:
O. Shebanova
Author:
P.F. McMillan
Author:
M.T. Weller
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics
