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Fluctuations and Landau-Devonshire expansion for barium titanate

A. I. Sokolov·A. K. Tagantsev
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Abstract

The experimentally observed temperature dependence of the quartic coefficients in the Landau-Devonshire expansion for BaTiO_3 is naturally accounted for within a proper fluctuation model. It is explained, in particular, why one of the quartic coefficients varies with temperature above T_c while the second is constant. The tetragonal phase in BaTiO_3 is argued to exist essentially due to the thermal fluctuations, while the true Landau-Devonshire expansion with temperature-independent coefficients favours the rhombohedral ferroelectric phase. Certain conclusions concerning the temperature dependence of the sextic Landau-Devonshire coefficients are also made.

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A. I. Sokolov, A. K. Tagantsev. 2002-04-18. Fluctuations and Landau-Devonshire expansion for barium titanate. https://doi.org/10.1134/1.1490011

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