Unexpected phase transition sequence in the ferroelectric Bi4Ti3O12
The high-temperature phase behaviour of the ferroelectric layered perovskite Bi4Ti3O12 has been re-examined by high-resolution powder neutron diffraction. Previous studies, both experimental and theoretical, had suggested conflicting structural models and phase transition sequences, exacerbated by t...
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doaj-a7804641901344ccbb9d191d165d6d262020-11-25T03:22:03ZengInternational Union of CrystallographyIUCrJ2052-25252019-05-016343844610.1107/S2052252519003804lc5103Unexpected phase transition sequence in the ferroelectric Bi4Ti3O12Yuan-Yuan Guo0Alexandra S. Gibbs1J. Manuel Perez-Mato2Philip Lightfoot3School of Chemistry and EaStCHEM, University of St Andrews, St Andrews KY16 9ST, ScotlandISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Harwell OX11 0QX, UKDept. of Condensed Matter Physics, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, SpainSchool of Chemistry and EaStCHEM, University of St Andrews, St Andrews KY16 9ST, ScotlandThe high-temperature phase behaviour of the ferroelectric layered perovskite Bi4Ti3O12 has been re-examined by high-resolution powder neutron diffraction. Previous studies, both experimental and theoretical, had suggested conflicting structural models and phase transition sequences, exacerbated by the complex interplay of several competing structural instabilities. This study confirms that Bi4Ti3O12 undergoes two separate structural transitions from the aristotype tetragonal phase (space group I4/mmm) to the ambient-temperature ferroelectric phase (confirmed as monoclinic, B1a1). An unusual, and previously unconsidered, intermediate paraelectric phase is suggested to exist above TC with tetragonal symmetry, space group P4/mbm. This phase is peculiar in displaying a unique type of octahedral tilting, in which the triple perovskite blocks of the layered structure alternate between tilted and untilted. This is rationalized in terms of the bonding requirements of the Bi3+ cations within the perovskite blocks.http://scripts.iucr.org/cgi-bin/paper?S2052252519003804perovskitesferroelectricspowder neutron diffraction |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Yuan-Yuan Guo Alexandra S. Gibbs J. Manuel Perez-Mato Philip Lightfoot |
spellingShingle |
Yuan-Yuan Guo Alexandra S. Gibbs J. Manuel Perez-Mato Philip Lightfoot Unexpected phase transition sequence in the ferroelectric Bi4Ti3O12 IUCrJ perovskites ferroelectrics powder neutron diffraction |
author_facet |
Yuan-Yuan Guo Alexandra S. Gibbs J. Manuel Perez-Mato Philip Lightfoot |
author_sort |
Yuan-Yuan Guo |
title |
Unexpected phase transition sequence in the ferroelectric Bi4Ti3O12 |
title_short |
Unexpected phase transition sequence in the ferroelectric Bi4Ti3O12 |
title_full |
Unexpected phase transition sequence in the ferroelectric Bi4Ti3O12 |
title_fullStr |
Unexpected phase transition sequence in the ferroelectric Bi4Ti3O12 |
title_full_unstemmed |
Unexpected phase transition sequence in the ferroelectric Bi4Ti3O12 |
title_sort |
unexpected phase transition sequence in the ferroelectric bi4ti3o12 |
publisher |
International Union of Crystallography |
series |
IUCrJ |
issn |
2052-2525 |
publishDate |
2019-05-01 |
description |
The high-temperature phase behaviour of the ferroelectric layered perovskite Bi4Ti3O12 has been re-examined by high-resolution powder neutron diffraction. Previous studies, both experimental and theoretical, had suggested conflicting structural models and phase transition sequences, exacerbated by the complex interplay of several competing structural instabilities. This study confirms that Bi4Ti3O12 undergoes two separate structural transitions from the aristotype tetragonal phase (space group I4/mmm) to the ambient-temperature ferroelectric phase (confirmed as monoclinic, B1a1). An unusual, and previously unconsidered, intermediate paraelectric phase is suggested to exist above TC with tetragonal symmetry, space group P4/mbm. This phase is peculiar in displaying a unique type of octahedral tilting, in which the triple perovskite blocks of the layered structure alternate between tilted and untilted. This is rationalized in terms of the bonding requirements of the Bi3+ cations within the perovskite blocks. |
topic |
perovskites ferroelectrics powder neutron diffraction |
url |
http://scripts.iucr.org/cgi-bin/paper?S2052252519003804 |
work_keys_str_mv |
AT yuanyuanguo unexpectedphasetransitionsequenceintheferroelectricbi4ti3o12 AT alexandrasgibbs unexpectedphasetransitionsequenceintheferroelectricbi4ti3o12 AT jmanuelperezmato unexpectedphasetransitionsequenceintheferroelectricbi4ti3o12 AT philiplightfoot unexpectedphasetransitionsequenceintheferroelectricbi4ti3o12 |
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1724611556643176448 |