Order-disorder octahedral tilting transition in SrSnO3 perovskite

Mountstevens, E. H. and Redfern, S. A. T. and Attfield, J. P. (2005) Order-disorder octahedral tilting transition in SrSnO3 perovskite. Physical Review B, 71 (22). DOI https://doi.org/10.1103/PhysRevB.71.220102

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High-temperature powder neutron diffraction has been used to characterize two structural phase transitions in the perovskite SrSnO3. A continuous orthorhombic Pnma to Imma symmetry transition occurs at 636 °C, and a first-order transition to a tetragonal I4∕mcm phase occurs at 800 °C. Such octahedral tilting transitions are very common in perovskite oxides and are generally assumed to be displacive. However, a displacive description of the transitions in SrSnO3 gives physically unrealistic results, and a considerable dynamic order-disorder component is found. A more realistic order-disorder modeling shows that the population difference between majority and minority tilt states is an appropriate order parameter, and the onset of tilting fluctuations ∼300 °C below the Pnma to Imma transition leads to an unusual divergence of the lattice parameters on warming towards the transition.

Item Type: Article
Uncontrolled Keywords: 2005 AREP 2005 P IA48
Subjects: 03 - Mineral Sciences
Divisions: 03 - Mineral Sciences
Journal or Publication Title: Physical Review B
Volume: 71
Identification Number: https://doi.org/10.1103/PhysRevB.71.220102
Depositing User: Sarah Humbert
Date Deposited: 12 Nov 2010 14:37
Last Modified: 23 Jul 2013 09:59
URI: http://eprints.esc.cam.ac.uk/id/eprint/1762

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