- Title
- Symmetry rules and strain/order-parameter relationships for coupling between octahedral tilting and cooperative Jahn-Teller transitions in ABX₃ perovskites: I. theory
- Creator
- Carpenter, Michael A.; Howard, Christopher J.
- Relation
- Acta Crystallographica Section B: Structural Science Vol. 65, Issue 2, p. 134-146
- Publisher Link
- http://dx.doi.org/10.1107/S0108768109000974
- Publisher
- International Union of Crystallography
- Resource Type
- journal article
- Date
- 2009
- Description
- Space groups, order-parameter and strain/order-parameter coupling relationships in ABX₃ perovskite structures which combine cooperative Jahn-Teller distortions and octahedral tilting have been investigated from the perspective of group theory using the computer program ISOTROPY. Two common Jahn-Teller ordering schemes are associated with the irreducible representations M₂⁺ and R₃⁺ of the space group Pm3̅m. A third, less-common ordering scheme is associated withᴦ₃⁺. These combine with tilting instabilities associated with M₃⁺ and R₄⁺ to generate a predicted suite of Jahn-Teller structure types that includes many of the known structures of manganites, vanadates, Cu and Cr halides. Order-parameter coupling and possible phase transitions are described using Landau free-energy expansions, and general expressions for the relationships between symmetry-adapted spontaneous strains and particular order-parameter components are presented. These provide a general formal framework for determining structural evolution across multi-component order-parameter space and for characterizing the influence of tilting instabilities on Jahn-Teller instabilities or of Jahn-Teller ordering on octahedral tilting.
- Subject
- symmetry; strain/order-parameter relationship; coupling; ordering schemes; perovskites; Jahn-Teller cations; phase transitions
- Identifier
- http://hdl.handle.net/1959.13/916987
- Identifier
- uon:8173
- Identifier
- ISSN:0108-7681
- Language
- eng
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