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arXiv · 1512.03643

Emergence of long-range order in BaTiO3 from local symmetry-breaking distortions

M. S. Senn·D. A. Keen·T. C. A. Lucas·J. A. Hriljac·A. L. Goodwin
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Abstract

By using a symmetry motivated basis to evaluate local distortions against pair distribution function data (PDF), we show without prior bias, that the off-centre Ti displacements in the archetypal ferroelectric BaTiO3 are zone centred and rhombohedral-like in nature across its known ferroelectric and paraelectric phases. With our newly-gained insight we construct a simple Monte Carlo (MC) model which captures our main experimental findings and demonstrate how the rich crystallographic phase diagram of BaTiO3 emerges from correlations of local symmetry-breaking distortions alone. Our results strongly support the order-disorder picture for these phase transitions, but can also be reconciled with the soft-mode theory of BaTiO3 that is supported by some spectroscopic techniques.

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M. S. Senn, D. A. Keen, T. C. A. Lucas, J. A. Hriljac, A. L. Goodwin. 2015-12-11. Emergence of long-range order in BaTiO3 from local symmetry-breaking distortions. https://doi.org/10.1103/physrevlett.116.207602

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